diff --git a/src/app/app_menus.cpp b/src/app/app_menus.cpp
index 52eac793c..04d1659c8 100644
--- a/src/app/app_menus.cpp
+++ b/src/app/app_menus.cpp
@@ -65,7 +65,7 @@ AppMenus::AppMenus()
 void AppMenus::reload()
 {
   XmlDocumentRef doc(GuiXml::instance()->doc());
-  TiXmlHandle handle(doc);
+  TiXmlHandle handle(doc.get());
   const char* path = GuiXml::instance()->filename();
 
   ////////////////////////////////////////
diff --git a/src/app/cmd/add_frame.cpp b/src/app/cmd/add_frame.cpp
index 2c1bea8f4..51d7c6633 100644
--- a/src/app/cmd/add_frame.cpp
+++ b/src/app/cmd/add_frame.cpp
@@ -45,7 +45,7 @@ void AddFrame::onExecute()
     LayerImage* bglayer = sprite->backgroundLayer();
     if (bglayer) {
       ImageRef bgimage(Image::create(sprite->pixelFormat(), sprite->width(), sprite->height()));
-      clear_image(bgimage, doc->bgColor(bglayer));
+      clear_image(bgimage.get(), doc->bgColor(bglayer));
       Cel* cel = new Cel(m_newFrame, bgimage);
       m_addCel.reset(new cmd::AddCel(bglayer, cel));
       m_addCel->execute(context());
diff --git a/src/app/cmd/background_from_layer.cpp b/src/app/cmd/background_from_layer.cpp
index ac0dfc0eb..72ae2d808 100644
--- a/src/app/cmd/background_from_layer.cpp
+++ b/src/app/cmd/background_from_layer.cpp
@@ -57,8 +57,8 @@ void BackgroundFromLayer::onExecute()
     Image* cel_image = cel->image();
     ASSERT(cel_image);
 
-    clear_image(bg_image, bgcolor);
-    render::composite_image(bg_image, cel_image,
+    clear_image(bg_image.get(), bgcolor);
+    render::composite_image(bg_image.get(), cel_image,
       cel->x(), cel->y(),
       MID(0, cel->opacity(), 255),
       static_cast<LayerImage*>(layer)->getBlendMode());
@@ -69,11 +69,11 @@ void BackgroundFromLayer::onExecute()
     // same size of cel-image and bg-image
     if (bg_image->width() == cel_image->width() &&
         bg_image->height() == cel_image->height()) {
-      executeAndAdd(new CopyRect(cel_image, bg_image,
+      executeAndAdd(new CopyRect(cel_image, bg_image.get(),
           gfx::Clip(0, 0, cel_image->bounds())));
     }
     else {
-      ImageRef bg_image2(Image::createCopy(bg_image));
+      ImageRef bg_image2(Image::createCopy(bg_image.get()));
       executeAndAdd(new cmd::ReplaceImage(sprite, cel->imageRef(), bg_image2));
     }
   }
@@ -84,7 +84,7 @@ void BackgroundFromLayer::onExecute()
     if (!cel) {
       ImageRef cel_image(Image::create(sprite->pixelFormat(),
           sprite->width(), sprite->height()));
-      clear_image(cel_image, bgcolor);
+      clear_image(cel_image.get(), bgcolor);
 
       // Create the new cel and add it to the new background layer
       cel = new Cel(frame, cel_image);
diff --git a/src/app/cmd/clear_image.cpp b/src/app/cmd/clear_image.cpp
index c45ce2b40..b9c6ddaf6 100644
--- a/src/app/cmd/clear_image.cpp
+++ b/src/app/cmd/clear_image.cpp
@@ -35,8 +35,8 @@ void ClearImage::onExecute()
 
 void ClearImage::onUndo()
 {
-  copy_image(image(), m_copy);
-  m_copy.reset(nullptr);
+  copy_image(image(), m_copy.get());
+  m_copy.reset();
 }
 
 } // namespace cmd
diff --git a/src/app/cmd/clear_mask.cpp b/src/app/cmd/clear_mask.cpp
index a0b892919..f5f5fdc7b 100644
--- a/src/app/cmd/clear_mask.cpp
+++ b/src/app/cmd/clear_mask.cpp
@@ -113,7 +113,7 @@ void ClearMask::clear()
 
 void ClearMask::restore()
 {
-  copy_image(m_dstImage->image(), m_copy, m_offsetX, m_offsetY);
+  copy_image(m_dstImage->image(), m_copy.get(), m_offsetX, m_offsetY);
 }
 
 } // namespace cmd
diff --git a/src/app/cmd/copy_cel.cpp b/src/app/cmd/copy_cel.cpp
index dba78899d..697c79161 100644
--- a/src/app/cmd/copy_cel.cpp
+++ b/src/app/cmd/copy_cel.cpp
@@ -95,10 +95,10 @@ void CopyCel::onExecute()
       int blend = (srcLayer->isBackground() ?
         BLEND_MODE_COPY: BLEND_MODE_NORMAL);
 
-      ImageRef tmp(Image::createCopy(dstImage));
-      render::composite_image(tmp, srcImage,
+      ImageRef tmp(Image::createCopy(dstImage.get()));
+      render::composite_image(tmp.get(), srcImage,
         srcCel->x(), srcCel->y(), 255, blend);
-      executeAndAdd(new cmd::CopyRect(dstImage, tmp, gfx::Clip(tmp->bounds())));
+      executeAndAdd(new cmd::CopyRect(dstImage.get(), tmp.get(), gfx::Clip(tmp->bounds())));
     }
   }
   // For transparent layers
diff --git a/src/app/cmd/deselect_mask.cpp b/src/app/cmd/deselect_mask.cpp
index eb5089f6e..bed893258 100644
--- a/src/app/cmd/deselect_mask.cpp
+++ b/src/app/cmd/deselect_mask.cpp
@@ -37,7 +37,7 @@ void DeselectMask::onUndo()
   doc->setMask(m_oldMask);
   doc->setMaskVisible(true);
 
-  m_oldMask.reset(nullptr);
+  m_oldMask.reset();
 }
 
 size_t DeselectMask::onMemSize() const
diff --git a/src/app/cmd/flatten_layers.cpp b/src/app/cmd/flatten_layers.cpp
index 194b552d8..1c94b9003 100644
--- a/src/app/cmd/flatten_layers.cpp
+++ b/src/app/cmd/flatten_layers.cpp
@@ -57,8 +57,8 @@ void FlattenLayers::onExecute()
   // Copy all frames to the background.
   for (frame_t frame(0); frame<sprite->totalFrames(); ++frame) {
     // Clear the image and render this frame.
-    clear_image(image, bgcolor);
-    render.renderSprite(image, sprite, frame);
+    clear_image(image.get(), bgcolor);
+    render.renderSprite(image.get(), sprite, frame);
 
     // TODO Keep cel links when possible
 
@@ -71,11 +71,11 @@ void FlattenLayers::onExecute()
       cel_image = cel->imageRef();
       ASSERT(cel_image);
 
-      executeAndAdd(new cmd::CopyRect(cel_image, image,
+      executeAndAdd(new cmd::CopyRect(cel_image.get(), image.get(),
           gfx::Clip(0, 0, image->bounds())));
     }
     else {
-      cel_image.reset(Image::createCopy(image));
+      cel_image.reset(Image::createCopy(image.get()));
       cel = new Cel(frame, cel_image);
       background->addCel(cel);
     }
diff --git a/src/app/cmd/move_cel.cpp b/src/app/cmd/move_cel.cpp
index 5d3a4f91d..ac6b2436d 100644
--- a/src/app/cmd/move_cel.cpp
+++ b/src/app/cmd/move_cel.cpp
@@ -98,10 +98,10 @@ void MoveCel::onExecute()
       int blend = (srcLayer->isBackground() ?
         BLEND_MODE_COPY: BLEND_MODE_NORMAL);
 
-      ImageRef tmp(Image::createCopy(dstImage));
-      render::composite_image(tmp, srcImage,
+      ImageRef tmp(Image::createCopy(dstImage.get()));
+      render::composite_image(tmp.get(), srcImage,
         srcCel->x(), srcCel->y(), 255, blend);
-      executeAndAdd(new cmd::CopyRect(dstImage, tmp, gfx::Clip(tmp->bounds())));
+      executeAndAdd(new cmd::CopyRect(dstImage.get(), tmp.get(), gfx::Clip(tmp->bounds())));
     }
     executeAndAdd(new cmd::ClearCel(srcCel));
   }
diff --git a/src/app/cmd/replace_image.cpp b/src/app/cmd/replace_image.cpp
index 44b7159d5..350809284 100644
--- a/src/app/cmd/replace_image.cpp
+++ b/src/app/cmd/replace_image.cpp
@@ -37,10 +37,10 @@ void ReplaceImage::onExecute()
   // modify/re-add this same image ID
   ImageRef oldImage = sprite()->getImageRef(m_oldImageId);
   ASSERT(oldImage);
-  m_copy.reset(Image::createCopy(oldImage));
+  m_copy.reset(Image::createCopy(oldImage.get()));
 
   sprite()->replaceImage(m_oldImageId, m_newImage);
-  m_newImage.reset(nullptr);
+  m_newImage.reset();
 }
 
 void ReplaceImage::onUndo()
@@ -51,7 +51,7 @@ void ReplaceImage::onUndo()
   m_copy->setId(m_oldImageId);
 
   sprite()->replaceImage(m_newImageId, m_copy);
-  m_copy.reset(Image::createCopy(newImage));
+  m_copy.reset(Image::createCopy(newImage.get()));
 }
 
 void ReplaceImage::onRedo()
@@ -62,7 +62,7 @@ void ReplaceImage::onRedo()
   m_copy->setId(m_newImageId);
 
   sprite()->replaceImage(m_oldImageId, m_copy);
-  m_copy.reset(Image::createCopy(oldImage));
+  m_copy.reset(Image::createCopy(oldImage.get()));
 }
 
 } // namespace cmd
diff --git a/src/app/cmd/reselect_mask.cpp b/src/app/cmd/reselect_mask.cpp
index 223c29d95..761ab8f15 100644
--- a/src/app/cmd/reselect_mask.cpp
+++ b/src/app/cmd/reselect_mask.cpp
@@ -29,7 +29,7 @@ void ReselectMask::onExecute()
 
   if (m_oldMask) {
     doc->setMask(m_oldMask);
-    m_oldMask.reset(nullptr);
+    m_oldMask.reset();
   }
 
   doc->setMaskVisible(true);
diff --git a/src/app/cmd/set_cel_data.cpp b/src/app/cmd/set_cel_data.cpp
index 7c24aaa60..f281a5655 100644
--- a/src/app/cmd/set_cel_data.cpp
+++ b/src/app/cmd/set_cel_data.cpp
@@ -39,7 +39,7 @@ void SetCelData::onExecute()
     createCopy();
 
   cel->setDataRef(m_newData);
-  m_newData.reset(nullptr);
+  m_newData.reset();
 }
 
 void SetCelData::onUndo()
@@ -52,7 +52,7 @@ void SetCelData::onUndo()
     m_dataCopy->image()->setId(m_oldImageId);
 
     cel->setDataRef(m_dataCopy);
-    m_dataCopy.reset(nullptr);
+    m_dataCopy.reset();
   }
   else {
     CelDataRef oldData = cel->sprite()->getCelDataRef(m_oldDataId);
diff --git a/src/app/commands/cmd_import_sprite_sheet.cpp b/src/app/commands/cmd_import_sprite_sheet.cpp
index 5dd88d0ae..92fbae537 100644
--- a/src/app/commands/cmd_import_sprite_sheet.cpp
+++ b/src/app/commands/cmd_import_sprite_sheet.cpp
@@ -267,7 +267,7 @@ retry:;
           Image::create(sprite->pixelFormat(), frameBounds.w, frameBounds.h));
 
         // Render the portion of sheet.
-        render.renderSprite(resultImage, sprite, currentFrame,
+        render.renderSprite(resultImage.get(), sprite, currentFrame,
           gfx::Clip(0, 0, x, y, frameBounds.w, frameBounds.h));
 
         animation.push_back(resultImage);
diff --git a/src/app/commands/cmd_merge_down_layer.cpp b/src/app/commands/cmd_merge_down_layer.cpp
index 6a154f517..47eca62be 100644
--- a/src/app/commands/cmd_merge_down_layer.cpp
+++ b/src/app/commands/cmd_merge_down_layer.cpp
@@ -94,7 +94,7 @@ void MergeDownLayerCommand::onExecute(Context* context)
     // With source image?
     if (src_image) {
       // No destination image
-      if (dst_image == NULL) {  // Only a transparent layer can have a null cel
+      if (!dst_image) {  // Only a transparent layer can have a null cel
         // Copy this cel to the destination layer...
 
         // Creating a copy of the image
@@ -122,13 +122,14 @@ void MergeDownLayerCommand::onExecute(Context* context)
 
         doc::color_t bgcolor = app_get_color_to_clear_layer(dst_layer);
 
-        ImageRef new_image(doc::crop_image(dst_image,
+        ImageRef new_image(doc::crop_image(
+            dst_image.get(),
             bounds.x-dst_cel->x(),
             bounds.y-dst_cel->y(),
             bounds.w, bounds.h, bgcolor));
 
         // Merge src_image in new_image
-        render::composite_image(new_image, src_image,
+        render::composite_image(new_image.get(), src_image,
           src_cel->x()-bounds.x,
           src_cel->y()-bounds.y,
           src_cel->opacity(),
diff --git a/src/app/commands/cmd_rotate.cpp b/src/app/commands/cmd_rotate.cpp
index 3b1d42db2..26324f7b6 100644
--- a/src/app/commands/cmd_rotate.cpp
+++ b/src/app/commands/cmd_rotate.cpp
@@ -111,7 +111,7 @@ protected:
         ImageRef new_image(Image::create(image->pixelFormat(),
             m_angle == 180 ? image->width(): image->height(),
             m_angle == 180 ? image->height(): image->width()));
-        doc::rotate_image(image, new_image, m_angle);
+        doc::rotate_image(image, new_image.get(), m_angle);
 
         api.replaceImage(m_sprite, cel->imageRef(), new_image);
       }
diff --git a/src/app/commands/cmd_sprite_size.cpp b/src/app/commands/cmd_sprite_size.cpp
index fdecf57e2..abaec5730 100644
--- a/src/app/commands/cmd_sprite_size.cpp
+++ b/src/app/commands/cmd_sprite_size.cpp
@@ -95,7 +95,7 @@ protected:
         ImageRef new_image(Image::create(image->pixelFormat(), MAX(1, w), MAX(1, h)));
 
         doc::algorithm::fixup_image_transparent_colors(image);
-        doc::algorithm::resize_image(image, new_image,
+        doc::algorithm::resize_image(image, new_image.get(),
           m_resize_method,
           m_sprite->palette(cel->frame()),
           m_sprite->rgbMap(cel->frame()));
@@ -125,7 +125,7 @@ protected:
         gfx::Rect(
           scale_x(m_document->mask()->bounds().x-1),
           scale_y(m_document->mask()->bounds().y-1), MAX(1, w), MAX(1, h)));
-      algorithm::resize_image(old_bitmap, new_mask->bitmap(),
+      algorithm::resize_image(old_bitmap.get(), new_mask->bitmap(),
           m_resize_method,
           m_sprite->palette(0), // Ignored
           m_sprite->rgbMap(0)); // Ignored
diff --git a/src/app/commands/filters/cmd_convolution_matrix.cpp b/src/app/commands/filters/cmd_convolution_matrix.cpp
index 6fcbc6966..fa092d090 100644
--- a/src/app/commands/filters/cmd_convolution_matrix.cpp
+++ b/src/app/commands/filters/cmd_convolution_matrix.cpp
@@ -181,14 +181,14 @@ void ConvolutionMatrixCommand::onExecute(Context* context)
 
   ConvolutionMatrixFilter filter;
   filter.setTiledMode(docPref.tiled.mode());
-  if (matrix != 0)
+  if (matrix)
     filter.setMatrix(matrix);
 
   FilterManagerImpl filterMgr(context, &filter);
 
   ConvolutionMatrixWindow window(filter, filterMgr, m_stock);
   if (window.doModal()) {
-    if (filter.getMatrix() != NULL)
+    if (filter.getMatrix())
       set_config_string(ConfigSection, "Selected", filter.getMatrix()->getName());
   }
 }
diff --git a/src/app/commands/filters/convolution_matrix_stock.cpp b/src/app/commands/filters/convolution_matrix_stock.cpp
index 5134ca69b..69a690418 100644
--- a/src/app/commands/filters/convolution_matrix_stock.cpp
+++ b/src/app/commands/filters/convolution_matrix_stock.cpp
@@ -68,7 +68,8 @@ void ConvolutionMatrixStock::reloadStock()
 
     while (rf.next()) {
       // Open matrices stock file
-      base::FileHandle f = base::open_file(rf.filename(), "r");
+      base::FileHandle handle(base::open_file(rf.filename(), "r"));
+      FILE* f = handle.get();
       if (!f)
         continue;
 
diff --git a/src/app/commands/filters/filter_worker.cpp b/src/app/commands/filters/filter_worker.cpp
index 729a0706d..b7bfac340 100644
--- a/src/app/commands/filters/filter_worker.cpp
+++ b/src/app/commands/filters/filter_worker.cpp
@@ -91,7 +91,7 @@ FilterWorker::FilterWorker(FilterManagerImpl* filterMgr)
 
 FilterWorker::~FilterWorker()
 {
-  if (m_alertWindow != NULL)
+  if (m_alertWindow)
     m_alertWindow->closeWindow(NULL);
 
   delete m_progressBar;
diff --git a/src/app/document_range_tests.cpp b/src/app/document_range_tests.cpp
index 414aadd12..528ad98e4 100644
--- a/src/app/document_range_tests.cpp
+++ b/src/app/document_range_tests.cpp
@@ -115,8 +115,8 @@ public:
           layer->addCel(cel);
         }
 
-        clear_image(image, black);
-        put_pixel(image, i, j, white);
+        clear_image(image.get(), black);
+        put_pixel(image.get(), i, j, white);
       }
     }
   }
diff --git a/src/app/file/ase_format.cpp b/src/app/file/ase_format.cpp
index c0e12a5e7..2087cfdb6 100644
--- a/src/app/file/ase_format.cpp
+++ b/src/app/file/ase_format.cpp
@@ -150,7 +150,8 @@ FileFormat* CreateAseFormat()
 
 bool AseFormat::onLoad(FileOp* fop)
 {
-  FileHandle f(open_file_with_exception(fop->filename, "rb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "rb"));
+  FILE* f = handle.get();
 
   ASE_Header header;
   if (!ase_file_read_header(f, &header)) {
@@ -295,7 +296,8 @@ bool AseFormat::onLoad(FileOp* fop)
 bool AseFormat::onSave(FileOp* fop)
 {
   Sprite* sprite = fop->document->sprite();
-  FileHandle f(open_file_with_exception(fop->filename, "wb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "wb"));
+  FILE* f = handle.get();
 
   // Write the header
   ASE_Header header;
@@ -1037,15 +1039,15 @@ static Cel* ase_file_read_cel_chunk(FILE* f, Sprite* sprite, frame_t frame,
         switch (image->pixelFormat()) {
 
           case IMAGE_RGB:
-            read_raw_image<RgbTraits>(f, image, fop, header);
+            read_raw_image<RgbTraits>(f, image.get(), fop, header);
             break;
 
           case IMAGE_GRAYSCALE:
-            read_raw_image<GrayscaleTraits>(f, image, fop, header);
+            read_raw_image<GrayscaleTraits>(f, image.get(), fop, header);
             break;
 
           case IMAGE_INDEXED:
-            read_raw_image<IndexedTraits>(f, image, fop, header);
+            read_raw_image<IndexedTraits>(f, image.get(), fop, header);
             break;
         }
 
@@ -1096,15 +1098,15 @@ static Cel* ase_file_read_cel_chunk(FILE* f, Sprite* sprite, frame_t frame,
           switch (image->pixelFormat()) {
 
             case IMAGE_RGB:
-              read_compressed_image<RgbTraits>(f, image, chunk_end, fop, header);
+              read_compressed_image<RgbTraits>(f, image.get(), chunk_end, fop, header);
               break;
 
             case IMAGE_GRAYSCALE:
-              read_compressed_image<GrayscaleTraits>(f, image, chunk_end, fop, header);
+              read_compressed_image<GrayscaleTraits>(f, image.get(), chunk_end, fop, header);
               break;
 
             case IMAGE_INDEXED:
-              read_compressed_image<IndexedTraits>(f, image, chunk_end, fop, header);
+              read_compressed_image<IndexedTraits>(f, image.get(), chunk_end, fop, header);
               break;
           }
         }
diff --git a/src/app/file/bmp_format.cpp b/src/app/file/bmp_format.cpp
index c216e0058..3f6da0239 100644
--- a/src/app/file/bmp_format.cpp
+++ b/src/app/file/bmp_format.cpp
@@ -602,7 +602,8 @@ bool BmpFormat::onLoad(FileOp *fop)
   PixelFormat pixelFormat;
   int format;
 
-  FileHandle f(open_file_with_exception(fop->filename, "rb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "rb"));
+  FILE* f = handle.get();
 
   if (read_bmfileheader(f, &fileheader) != 0)
     return false;
@@ -692,7 +693,7 @@ bool BmpFormat::onLoad(FileOp *fop)
   }
 
   // Setup the file-data.
-  if (fop->seq.format_options == NULL) {
+  if (!fop->seq.format_options) {
     base::SharedPtr<BmpOptions> bmp_options(new BmpOptions());
 
     bmp_options->format = format;
@@ -711,7 +712,7 @@ bool BmpFormat::onLoad(FileOp *fop)
 #ifdef ENABLE_SAVE
 bool BmpFormat::onSave(FileOp *fop)
 {
-  Image *image = fop->seq.image;
+  Image* image = fop->seq.image.get();
   int bfSize;
   int biSizeImage;
   int bpp = (image->pixelFormat() == IMAGE_RGB) ? 24 : 8;
@@ -729,7 +730,8 @@ bool BmpFormat::onSave(FileOp *fop)
     bfSize = 54 + biSizeImage;       /* header + image data */
   }
 
-  FileHandle f(open_file_with_exception(fop->filename, "wb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "wb"));
+  FILE* f = handle.get();
 
   /* file_header */
   fputw(0x4D42, f);              /* bfType ("BM") */
diff --git a/src/app/file/file.cpp b/src/app/file/file.cpp
index 4ff0a2a7b..ceb8e3899 100644
--- a/src/app/file/file.cpp
+++ b/src/app/file/file.cpp
@@ -422,7 +422,7 @@ FileOp* fop_to_save_document(Context* context, Document* document, const char* f
     base::SharedPtr<FormatOptions> format_options = fop->format->getFormatOptions(fop);
 
     // Does the user cancelled the operation?
-    if (format_options == NULL) {
+    if (!format_options) {
       fop_free(fop);
       return NULL;
     }
@@ -472,7 +472,7 @@ void fop_operate(FileOp *fop, IFileOpProgress* progress)
           fop->document->sprite()->setPalette(fop->seq.palette, true);  \
         }                                                               \
                                                                         \
-        old_image = fop->seq.image;                                     \
+        old_image = fop->seq.image.get();                               \
         fop->seq.image.reset(NULL);                                     \
         fop->seq.last_cel = NULL;                                       \
       } while (0)
@@ -480,7 +480,7 @@ void fop_operate(FileOp *fop, IFileOpProgress* progress)
       // Load the sequence
       frame_t frames(fop->seq.filename_list.size());
       frame_t frame(0);
-      old_image = NULL;
+      old_image = nullptr;
 
       fop->seq.has_alpha = false;
       fop->seq.progress_offset = 0.0f;
@@ -502,10 +502,10 @@ void fop_operate(FileOp *fop, IFileOpProgress* progress)
         if (!old_image) {
           // Error reading the first frame
           if (!loadres || !fop->document || !fop->seq.last_cel) {
-            delete fop->seq.image;
+            fop->seq.image.reset();
             delete fop->seq.last_cel;
             delete fop->document;
-            fop->document = NULL;
+            fop->document = nullptr;
             break;
           }
           // Read ok
@@ -518,7 +518,7 @@ void fop_operate(FileOp *fop, IFileOpProgress* progress)
         else {
           // All done (or maybe not enough memory)
           if (!loadres || !fop->seq.last_cel) {
-            delete fop->seq.image;
+            fop->seq.image.reset();
             delete fop->seq.last_cel;
             break;
           }
@@ -594,7 +594,7 @@ void fop_operate(FileOp *fop, IFileOpProgress* progress)
       render::Render render;
       for (frame_t frame(0); frame < sprite->totalFrames(); ++frame) {
         // Draw the "frame" in "fop->seq.image"
-        render.renderSprite(fop->seq.image, sprite, frame);
+        render.renderSprite(fop->seq.image.get(), sprite, frame);
 
         // Setup the palette.
         sprite->palette(frame)->copyColorsTo(fop->seq.palette);
@@ -702,7 +702,7 @@ void fop_post_load(FileOp* fop)
           frame_t(0), NULL));
 
       fop->document->sprite()->resetPalettes();
-      fop->document->sprite()->setPalette(palette, false);
+      fop->document->sprite()->setPalette(palette.get(), false);
     }
   }
 
@@ -711,7 +711,7 @@ void fop_post_load(FileOp* fop)
 
 void fop_sequence_set_format_options(FileOp* fop, const base::SharedPtr<FormatOptions>& format_options)
 {
-  ASSERT(fop->seq.format_options == NULL);
+  ASSERT(!fop->seq.format_options);
   fop->seq.format_options = format_options;
 }
 
diff --git a/src/app/file/fli_format.cpp b/src/app/file/fli_format.cpp
index 54a5e51e1..618af2599 100644
--- a/src/app/file/fli_format.cpp
+++ b/src/app/file/fli_format.cpp
@@ -74,7 +74,8 @@ bool FliFormat::onLoad(FileOp* fop)
 #endif
 
   // Open the file to read in binary mode
-  FileHandle f(open_file_with_exception(fop->filename, "rb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "rb"));
+  FILE* f = handle.get();
 
   fli_read_header(f, &fli_header);
   fseek(f, 128, SEEK_SET);
@@ -201,7 +202,8 @@ bool FliFormat::onSave(FileOp* fop)
   fli_header.oframe1 = fli_header.oframe2 = 0;
 
   /* open the file to write in binary mode */
-  FileHandle f(open_file_with_exception(fop->filename, "wb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "wb"));
+  FILE* f = handle.get();
 
   fseek(f, 128, SEEK_SET);
 
diff --git a/src/app/file/gif_format.cpp b/src/app/file/gif_format.cpp
index b8548121a..bff053862 100644
--- a/src/app/file/gif_format.cpp
+++ b/src/app/file/gif_format.cpp
@@ -776,7 +776,7 @@ bool GifFormat::onSave(FileOp* fop)
 base::SharedPtr<FormatOptions> GifFormat::onGetFormatOptions(FileOp* fop)
 {
   base::SharedPtr<GifOptions> gif_options;
-  if (fop->document->getFormatOptions() != NULL)
+  if (fop->document->getFormatOptions())
     gif_options = base::SharedPtr<GifOptions>(fop->document->getFormatOptions());
 
   if (!gif_options)
diff --git a/src/app/file/ico_format.cpp b/src/app/file/ico_format.cpp
index 7fbf510f0..db66ff09f 100644
--- a/src/app/file/ico_format.cpp
+++ b/src/app/file/ico_format.cpp
@@ -80,7 +80,8 @@ struct BITMAPINFOHEADER {
 
 bool IcoFormat::onLoad(FileOp* fop)
 {
-  FileHandle f(open_file_with_exception(fop->filename, "rb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "rb"));
+  FILE* f = handle.get();
 
   // Read the icon header
   ICONDIR header;
@@ -132,7 +133,7 @@ bool IcoFormat::onLoad(FileOp* fop)
   ImageRef image(Image::create(pixelFormat, width, height));
   Cel* cel = new Cel(frame_t(0), image);
   layer->addCel(cel);
-  clear_image(image, 0);
+  clear_image(image.get(), 0);
 
   // Go to the entry start in the file
   fseek(f, entry.image_offset, SEEK_SET);
@@ -178,16 +179,16 @@ bool IcoFormat::onLoad(FileOp* fop)
           c = fgetc(f);
           ASSERT(c >= 0 && c < numcolors);
           if (c >= 0 && c < numcolors)
-            put_pixel(image, x, y, c);
+            put_pixel(image.get(), x, y, c);
           else
-            put_pixel(image, x, y, 0);
+            put_pixel(image.get(), x, y, 0);
           break;
 
         case 24:
           b = fgetc(f);
           g = fgetc(f);
           r = fgetc(f);
-          put_pixel(image, x, y, rgba(r, g, b, 255));
+          put_pixel(image.get(), x, y, rgba(r, g, b, 255));
           break;
       }
     }
@@ -207,7 +208,7 @@ bool IcoFormat::onLoad(FileOp* fop)
       v = 128;
       for (b=0; b<8; b++) {
         if ((m & v) == v)
-          put_pixel(image, x*8+b, y, 0); // TODO mask color
+          put_pixel(image.get(), x*8+b, y, 0); // TODO mask color
         v >>= 1;
       }
     }
@@ -232,7 +233,8 @@ bool IcoFormat::onSave(FileOp* fop)
   int c, x, y, b, m, v;
   frame_t n, num = sprite->totalFrames();
 
-  FileHandle f(open_file_with_exception(fop->filename, "wb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "wb"));
+  FILE* f = handle.get();
 
   offset = 6 + num*16;  // ICONDIR + ICONDIRENTRYs
 
diff --git a/src/app/file/jpeg_format.cpp b/src/app/file/jpeg_format.cpp
index a510469d9..79fe61661 100644
--- a/src/app/file/jpeg_format.cpp
+++ b/src/app/file/jpeg_format.cpp
@@ -105,7 +105,8 @@ bool JpegFormat::onLoad(FileOp* fop)
   JDIMENSION buffer_height;
   int c;
 
-  FileHandle file(open_file_with_exception(fop->filename, "rb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "rb"));
+  FILE* file = handle.get();
 
   // Initialize the JPEG decompression object with error handling.
   jerr.fop = fop;
@@ -234,14 +235,15 @@ bool JpegFormat::onSave(FileOp* fop)
 {
   struct jpeg_compress_struct cinfo;
   struct error_mgr jerr;
-  Image *image = fop->seq.image;
+  Image* image = fop->seq.image.get();
   JSAMPARRAY buffer;
   JDIMENSION buffer_height;
   base::SharedPtr<JpegOptions> jpeg_options = fop->seq.format_options;
   int c;
 
   // Open the file for write in it.
-  FileHandle file(open_file_with_exception(fop->filename, "wb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "wb"));
+  FILE* file = handle.get();
 
   // Allocate and initialize JPEG compression object.
   jerr.fop = fop;
@@ -350,7 +352,7 @@ bool JpegFormat::onSave(FileOp* fop)
 base::SharedPtr<FormatOptions> JpegFormat::onGetFormatOptions(FileOp* fop)
 {
   base::SharedPtr<JpegOptions> jpeg_options;
-  if (fop->document->getFormatOptions() != NULL)
+  if (fop->document->getFormatOptions())
     jpeg_options = base::SharedPtr<JpegOptions>(fop->document->getFormatOptions());
 
   if (!jpeg_options)
diff --git a/src/app/file/pcx_format.cpp b/src/app/file/pcx_format.cpp
index 7ba825b4e..4a9eb280f 100644
--- a/src/app/file/pcx_format.cpp
+++ b/src/app/file/pcx_format.cpp
@@ -55,7 +55,8 @@ bool PcxFormat::onLoad(FileOp* fop)
   int x, y;
   char ch = 0;
 
-  FileHandle f(open_file_with_exception(fop->filename, "rb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "rb"));
+  FILE* f = handle.get();
 
   fgetc(f);                    /* skip manufacturer ID */
   fgetc(f);                    /* skip version flag */
@@ -178,7 +179,7 @@ bool PcxFormat::onLoad(FileOp* fop)
 #ifdef ENABLE_SAVE
 bool PcxFormat::onSave(FileOp* fop)
 {
-  Image *image = fop->seq.image;
+  Image* image = fop->seq.image.get();
   int c, r, g, b;
   int x, y;
   int runcount;
@@ -186,7 +187,8 @@ bool PcxFormat::onSave(FileOp* fop)
   char runchar;
   char ch = 0;
 
-  FileHandle f(open_file_with_exception(fop->filename, "wb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "wb"));
+  FILE* f = handle.get();
 
   if (image->pixelFormat() == IMAGE_RGB) {
     depth = 24;
diff --git a/src/app/file/png_format.cpp b/src/app/file/png_format.cpp
index 2b275d0b7..e169057cd 100644
--- a/src/app/file/png_format.cpp
+++ b/src/app/file/png_format.cpp
@@ -71,7 +71,8 @@ bool PngFormat::onLoad(FileOp* fop)
   png_bytep row_pointer;
   PixelFormat pixelFormat;
 
-  FileHandle fp(open_file_with_exception(fop->filename, "rb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "rb"));
+  FILE* fp = handle.get();
 
   /* Create and initialize the png_struct with the desired error handler
    * functions.  If you want to use the default stderr and longjump method,
@@ -321,7 +322,7 @@ bool PngFormat::onLoad(FileOp* fop)
 #ifdef ENABLE_SAVE
 bool PngFormat::onSave(FileOp* fop)
 {
-  Image *image = fop->seq.image;
+  Image* image = fop->seq.image.get();
   png_uint_32 width, height, y;
   png_structp png_ptr;
   png_infop info_ptr;
@@ -331,7 +332,8 @@ bool PngFormat::onSave(FileOp* fop)
   int pass, number_passes;
 
   /* open the file */
-  FileHandle fp(open_file_with_exception(fop->filename, "wb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "wb"));
+  FILE* fp = handle.get();
 
   /* Create and initialize the png_struct with the desired error handler
    * functions.  If you want to use the default stderr and longjump method,
diff --git a/src/app/file/tga_format.cpp b/src/app/file/tga_format.cpp
index 519c95270..cfac2fa33 100644
--- a/src/app/file/tga_format.cpp
+++ b/src/app/file/tga_format.cpp
@@ -197,7 +197,8 @@ bool TgaFormat::onLoad(FileOp* fop)
   unsigned int c, i, x, y, yc;
   int compressed;
 
-  FileHandle f(open_file_with_exception(fop->filename, "rb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "rb"));
+  FILE* f = handle.get();
 
   id_length = fgetc(f);
   palette_type = fgetc(f);
@@ -381,13 +382,14 @@ bool TgaFormat::onLoad(FileOp* fop)
 // should be an array of at least 256 RGB structures).
 bool TgaFormat::onSave(FileOp* fop)
 {
-  Image *image = fop->seq.image;
+  Image* image = fop->seq.image.get();
   unsigned char image_palette[256][3];
   int x, y, c, r, g, b;
   int depth = (image->pixelFormat() == IMAGE_RGB) ? 32 : 8;
   bool need_pal = (image->pixelFormat() == IMAGE_INDEXED)? true: false;
 
-  FileHandle f(open_file_with_exception(fop->filename, "wb"));
+  FileHandle handle(open_file_with_exception(fop->filename, "wb"));
+  FILE* f = handle.get();
 
   fputc(0, f);                          /* id length (no id saved) */
   fputc((need_pal) ? 1 : 0, f);         /* palette type */
diff --git a/src/app/flatten.cpp b/src/app/flatten.cpp
index 5b0ac0598..ddd5be5db 100644
--- a/src/app/flatten.cpp
+++ b/src/app/flatten.cpp
@@ -42,7 +42,7 @@ LayerImage* create_flatten_layer_copy(Sprite* dstSprite, const Layer* srcLayer,
       cel->setPosition(bounds.x, bounds.y);
 
       // Render this frame.
-      render.renderLayer(image, srcLayer, frame,
+      render.renderLayer(image.get(), srcLayer, frame,
         gfx::Clip(0, 0, bounds));
 
       // Add the cel (and release the base::UniquePtr).
diff --git a/src/app/gui_xml.cpp b/src/app/gui_xml.cpp
index 369fea258..6cf19a000 100644
--- a/src/app/gui_xml.cpp
+++ b/src/app/gui_xml.cpp
@@ -43,7 +43,7 @@ GuiXml::GuiXml()
 
 std::string GuiXml::version()
 {
-  TiXmlHandle handle(m_doc);
+  TiXmlHandle handle(m_doc.get());
   TiXmlElement* xmlKey = handle.FirstChild("gui").ToElement();
 
   if (xmlKey && xmlKey->Attribute("version")) {
diff --git a/src/app/job.cpp b/src/app/job.cpp
index 00424e11c..9f22ead9a 100644
--- a/src/app/job.cpp
+++ b/src/app/job.cpp
@@ -39,7 +39,7 @@ Job::Job(const char* jobName)
     m_progress = StatusBar::instance()->addProgress();
     m_alert_window = ui::Alert::create("%s<<Working...||&Cancel", jobName);
 
-    m_timer.reset(new ui::Timer(kMonitoringPeriod, m_alert_window));
+    m_timer.reset(new ui::Timer(kMonitoringPeriod, m_alert_window.get()));
     m_timer->Tick.connect(&Job::onMonitoringTick, this);
     m_timer->start();
   }
@@ -51,7 +51,7 @@ Job::~Job()
     ASSERT(!m_timer->isRunning());
     ASSERT(m_thread == NULL);
 
-    if (m_alert_window != NULL)
+    if (m_alert_window)
       m_alert_window->closeWindow(NULL);
 
     if (m_progress)
diff --git a/src/app/tools/tool_box.cpp b/src/app/tools/tool_box.cpp
index ebb0d6958..c3e365262 100644
--- a/src/app/tools/tool_box.cpp
+++ b/src/app/tools/tool_box.cpp
@@ -167,7 +167,7 @@ void ToolBox::loadTools()
   PRINTF("Loading Aseprite tools\n");
 
   XmlDocumentRef doc(GuiXml::instance()->doc());
-  TiXmlHandle handle(doc);
+  TiXmlHandle handle(doc.get());
 
   // For each group
   TiXmlElement* xmlGroup = handle.FirstChild("gui").FirstChild("tools").FirstChild("group").ToElement();
diff --git a/src/app/ui/editor/editor.cpp b/src/app/ui/editor/editor.cpp
index 30e80918d..93e58b769 100644
--- a/src/app/ui/editor/editor.cpp
+++ b/src/app/ui/editor/editor.cpp
@@ -205,7 +205,7 @@ void Editor::setStateInternal(const EditorStatePtr& newState)
   // Fire before change state event, set the state, and fire after
   // change state event.
   EditorState::BeforeChangeAction beforeChangeAction =
-    m_state->onBeforeChangeState(this, newState);
+    m_state->onBeforeChangeState(this, newState.get());
 
   // Push a new state
   if (newState) {
@@ -223,7 +223,7 @@ void Editor::setStateInternal(const EditorStatePtr& newState)
     m_state = m_statesHistory.top();
   }
 
-  ASSERT(m_state != NULL);
+  ASSERT(m_state);
 
   // Change to the new state.
   m_state->onAfterChangeState(this);
@@ -584,7 +584,7 @@ void Editor::drawSpriteClipped(const gfx::Region& updateRegion)
     for (const Rect& screenRect : screenRegion) {
       IntersectClip clip(&screenGraphics, screenRect);
       if (clip)
-        drawSpriteUnclippedRect(editorGraphics, updateRect);
+        drawSpriteUnclippedRect(editorGraphics.get(), updateRect);
     }
   }
 }
@@ -670,9 +670,9 @@ void Editor::drawMaskSafe()
     GraphicsPtr g = getGraphics(getClientBounds());
 
     for (const gfx::Rect& rc : region) {
-      IntersectClip clip(g, rc);
+      IntersectClip clip(g.get(), rc);
       if (clip)
-        drawMask(g);
+        drawMask(g.get());
     }
 
     // Draw the cursor
diff --git a/src/app/ui/editor/editor_states_history.cpp b/src/app/ui/editor/editor_states_history.cpp
index 50a5554bb..a9ae175cd 100644
--- a/src/app/ui/editor/editor_states_history.cpp
+++ b/src/app/ui/editor/editor_states_history.cpp
@@ -29,7 +29,7 @@ EditorStatePtr EditorStatesHistory::top()
 
 void EditorStatesHistory::push(const EditorStatePtr& state)
 {
-  ASSERT(state != NULL);
+  ASSERT(state);
   m_states.push_back(state);
 }
 
diff --git a/src/app/ui/editor/moving_pixels_state.cpp b/src/app/ui/editor/moving_pixels_state.cpp
index e86e6cac0..03573ac31 100644
--- a/src/app/ui/editor/moving_pixels_state.cpp
+++ b/src/app/ui/editor/moving_pixels_state.cpp
@@ -121,7 +121,7 @@ void MovingPixelsState::translate(const gfx::Point& delta)
 
 EditorState::BeforeChangeAction MovingPixelsState::onBeforeChangeState(Editor* editor, EditorState* newState)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   ASSERT(editor == m_editor);
 
   // If we are changing to another state, we've to drop the image.
@@ -153,7 +153,7 @@ EditorState::BeforeChangeAction MovingPixelsState::onBeforeChangeState(Editor* e
 
 void MovingPixelsState::onCurrentToolChange(Editor* editor)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   ASSERT(editor == m_editor);
 
   tools::Tool* current_tool = editor->getCurrentEditorTool();
@@ -170,7 +170,7 @@ void MovingPixelsState::onCurrentToolChange(Editor* editor)
 
 bool MovingPixelsState::onMouseDown(Editor* editor, MouseMessage* msg)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   ASSERT(editor == m_editor);
 
   // Set this editor as the active one and setup the ContextBar for
@@ -246,7 +246,7 @@ bool MovingPixelsState::onMouseDown(Editor* editor, MouseMessage* msg)
 
 bool MovingPixelsState::onMouseUp(Editor* editor, MouseMessage* msg)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   ASSERT(editor == m_editor);
 
   // Drop the image temporarily in this location (where the user releases the mouse)
@@ -261,7 +261,7 @@ bool MovingPixelsState::onMouseUp(Editor* editor, MouseMessage* msg)
 
 bool MovingPixelsState::onMouseMove(Editor* editor, MouseMessage* msg)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   ASSERT(editor == m_editor);
 
   // If there is a button pressed
@@ -305,7 +305,7 @@ bool MovingPixelsState::onMouseMove(Editor* editor, MouseMessage* msg)
 
 bool MovingPixelsState::onSetCursor(Editor* editor)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   ASSERT(editor == m_editor);
 
   // Move selection
@@ -321,7 +321,7 @@ bool MovingPixelsState::onSetCursor(Editor* editor)
 
 bool MovingPixelsState::onKeyDown(Editor* editor, KeyMessage* msg)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   if (!isActiveEditor())
     return false;
   ASSERT(editor == m_editor);
@@ -394,7 +394,7 @@ bool MovingPixelsState::onKeyDown(Editor* editor, KeyMessage* msg)
 
 bool MovingPixelsState::onKeyUp(Editor* editor, KeyMessage* msg)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   if (!isActiveEditor())
     return false;
   ASSERT(editor == m_editor);
@@ -405,7 +405,7 @@ bool MovingPixelsState::onKeyUp(Editor* editor, KeyMessage* msg)
 
 bool MovingPixelsState::onUpdateStatusBar(Editor* editor)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
   ASSERT(editor == m_editor);
 
   const gfx::Transformation& transform(getTransformation(editor));
@@ -501,10 +501,10 @@ void MovingPixelsState::onDropPixels(ContextBarObserver::DropAction action)
 
 void MovingPixelsState::setTransparentColor(const app::Color& color)
 {
-  ASSERT(m_pixelsMovement != NULL);
+  ASSERT(m_pixelsMovement);
 
   Layer* layer = m_editor->layer();
-  ASSERT(layer != NULL);
+  ASSERT(layer);
 
   m_pixelsMovement->setMaskColor(
     color_utils::color_for_target_mask(color, ColorTarget(layer)));
diff --git a/src/app/ui/keyboard_shortcuts.cpp b/src/app/ui/keyboard_shortcuts.cpp
index c0d067e55..fff165d96 100644
--- a/src/app/ui/keyboard_shortcuts.cpp
+++ b/src/app/ui/keyboard_shortcuts.cpp
@@ -454,7 +454,7 @@ void KeyboardShortcuts::importFile(TiXmlElement* rootElement, KeySource source)
 void KeyboardShortcuts::importFile(const std::string& filename, KeySource source)
 {
   XmlDocumentRef doc = app::open_xml(filename);
-  TiXmlHandle handle(doc);
+  TiXmlHandle handle(doc.get());
   TiXmlElement* xmlKey = handle.FirstChild("keyboard").ToElement();
 
   importFile(xmlKey, source);
diff --git a/src/app/ui/news_listbox.cpp b/src/app/ui/news_listbox.cpp
index f2610d19b..e536f9e27 100644
--- a/src/app/ui/news_listbox.cpp
+++ b/src/app/ui/news_listbox.cpp
@@ -254,7 +254,7 @@ void NewsListBox::parseFile(const std::string& filename)
     return;
   }
 
-  TiXmlHandle handle(doc);
+  TiXmlHandle handle(doc.get());
   TiXmlElement* itemXml = handle
     .FirstChild("rss")
     .FirstChild("channel")
diff --git a/src/app/ui/skin/skin_property.cpp b/src/app/ui/skin/skin_property.cpp
index b49402462..2186369fd 100644
--- a/src/app/ui/skin/skin_property.cpp
+++ b/src/app/ui/skin/skin_property.cpp
@@ -37,7 +37,7 @@ SkinPropertyPtr get_skin_property(ui::Widget* widget)
   SkinPropertyPtr skinProp;
 
   skinProp = widget->getProperty(SkinProperty::Name);
-  if (skinProp == NULL) {
+  if (!skinProp) {
     skinProp.reset(new SkinProperty);
     widget->setProperty(skinProp);
   }
diff --git a/src/app/ui/skin/skin_theme.cpp b/src/app/ui/skin/skin_theme.cpp
index a9017cc91..d63446f5d 100644
--- a/src/app/ui/skin/skin_theme.cpp
+++ b/src/app/ui/skin/skin_theme.cpp
@@ -369,7 +369,7 @@ void SkinTheme::onRegenerate()
     return;
 
   XmlDocumentRef doc = open_xml(rf.filename());
-  TiXmlHandle handle(doc);
+  TiXmlHandle handle(doc.get());
 
   // Load dimension
   {
@@ -491,7 +491,7 @@ void SkinTheme::onRegenerate()
       PRINTF("Loading part '%s'...\n", part_id);
 
       SkinPartPtr part = m_parts_by_id[part_id];
-      if (part == NULL)
+      if (!part)
         part = m_parts_by_id[part_id] = SkinPartPtr(new SkinPart);
 
       if (w > 0 && h > 0) {
@@ -911,7 +911,7 @@ void SkinTheme::paintButton(PaintEvent& ev)
   // Tool buttons are smaller
   LookType look = NormalLook;
   SkinPropertyPtr skinPropery = widget->getProperty(SkinProperty::Name);
-  if (skinPropery != NULL)
+  if (skinPropery)
     look = skinPropery->getLook();
 
   // Selected
@@ -986,7 +986,7 @@ void SkinTheme::paintCheckBox(PaintEvent& ev)
   // Check box look
   LookType look = NormalLook;
   SkinPropertyPtr skinPropery = widget->getProperty(SkinProperty::Name);
-  if (skinPropery != NULL)
+  if (skinPropery)
     look = skinPropery->getLook();
 
   // Background
@@ -1040,7 +1040,7 @@ void SkinTheme::paintEntry(PaintEvent& ev)
 
   bool isMiniLook = false;
   SkinPropertyPtr skinPropery = widget->getProperty(SkinProperty::Name);
-  if (skinPropery != NULL)
+  if (skinPropery)
     isMiniLook = (skinPropery->getLook() == MiniLook);
 
   gfx::Color bg = colors.background();
@@ -1403,11 +1403,11 @@ void SkinTheme::paintSlider(PaintEvent& ev)
   ISliderBgPainter* bgPainter = NULL;
 
   SkinPropertyPtr skinPropery = widget->getProperty(SkinProperty::Name);
-  if (skinPropery != NULL)
+  if (skinPropery)
     isMiniLook = (skinPropery->getLook() == MiniLook);
 
   SkinSliderPropertyPtr skinSliderPropery = widget->getProperty(SkinSliderProperty::Name);
-  if (skinSliderPropery != NULL)
+  if (skinSliderPropery)
     bgPainter = skinSliderPropery->getBgPainter();
 
   // Draw customized background
@@ -1649,7 +1649,7 @@ void SkinTheme::paintViewScrollbar(PaintEvent& ev)
 
   bool isMiniLook = false;
   SkinPropertyPtr skinPropery = widget->getProperty(SkinProperty::Name);
-  if (skinPropery != NULL)
+  if (skinPropery)
     isMiniLook = (skinPropery->getLook() == MiniLook);
 
   skin::Style* bgStyle = (isMiniLook ?
diff --git a/src/app/ui/skin/style.cpp b/src/app/ui/skin/style.cpp
index 07695fa9a..b86875ded 100644
--- a/src/app/ui/skin/style.cpp
+++ b/src/app/ui/skin/style.cpp
@@ -39,7 +39,7 @@ void BackgroundRule::onPaint(ui::Graphics* g, const gfx::Rect& bounds, const cha
 {
   SkinTheme* theme = static_cast<SkinTheme*>(ui::CurrentTheme::get());
 
-  if (m_part != NULL && m_part->size() > 0) {
+  if (m_part && m_part->size() > 0) {
     if (m_part->size() == 1) {
       if (!gfx::is_transparent(m_color))
         g->fillRect(m_color, bounds);
diff --git a/src/app/ui/skin/style_sheet.cpp b/src/app/ui/skin/style_sheet.cpp
index 573c6a712..63d3c5dcd 100644
--- a/src/app/ui/skin/style_sheet.cpp
+++ b/src/app/ui/skin/style_sheet.cpp
@@ -101,7 +101,7 @@ SkinPartPtr StyleSheet::convertPart(const css::Value& value)
   if (value.type() == css::Value::String) {
     const std::string& part_id = value.string();
     part = get_part_by_id(part_id);
-    if (part == NULL)
+    if (!part)
       throw base::Exception("Unknown part '%s'\n", part_id.c_str());
   }
   return part;
diff --git a/src/app/ui/tabs.cpp b/src/app/ui/tabs.cpp
index c8fd7818f..cfb7b7750 100644
--- a/src/app/ui/tabs.cpp
+++ b/src/app/ui/tabs.cpp
@@ -71,7 +71,7 @@ Tabs::Tabs(TabsDelegate* delegate)
 
 Tabs::~Tabs()
 {
-  m_removedTab.reset(nullptr);
+  m_removedTab.reset();
 
   // Stop animation
   stopAnimation();
@@ -104,7 +104,7 @@ void Tabs::removeTab(TabView* tabView, bool with_animation)
     return;
 
   if (m_hot == tab)
-    m_hot.reset(nullptr);
+    m_hot.reset();
 
   if (m_selected == tab) {
     if (tab == m_list.back())
@@ -113,7 +113,7 @@ void Tabs::removeTab(TabView* tabView, bool with_animation)
       selectNextTab();
 
     if (m_selected == tab)
-      m_selected.reset(nullptr);
+      m_selected.reset();
   }
 
   TabsListIterator it =
@@ -335,7 +335,7 @@ bool Tabs::onProcessMessage(Message* msg)
 
     case kMouseLeaveMessage:
       if (m_hot) {
-        m_hot.reset(nullptr);
+        m_hot.reset();
         invalidate();
       }
       return true;
@@ -756,8 +756,8 @@ void Tabs::stopDrag(DropTabResult result)
     case DropTabResult::DOCKED_IN_OTHER_PLACE: {
       TabPtr tab = m_floatingTab;
 
-      m_floatingTab.reset(nullptr);
-      m_removedTab.reset(nullptr);
+      m_floatingTab.reset();
+      m_removedTab.reset();
       destroyFloatingTab();
 
       //ASSERT(tab);      // TODO check this state
@@ -823,7 +823,7 @@ void Tabs::createFloatingTab(TabPtr& tab)
   resetOldPositions();
 
   m_floatingTab = tab;
-  m_removedTab.reset(nullptr);
+  m_removedTab.reset();
   startAnimation(ANI_REMOVING_TAB, ANI_REMOVING_TAB_TICKS);
   updateTabs();
 }
@@ -832,12 +832,12 @@ void Tabs::destroyFloatingTab()
 {
   if (m_floatingOverlay) {
     OverlayManager::instance()->removeOverlay(m_floatingOverlay.get());
-    m_floatingOverlay.reset(nullptr);
+    m_floatingOverlay.reset();
   }
 
   if (m_floatingTab) {
     TabPtr tab(m_floatingTab);
-    m_floatingTab.reset(nullptr);
+    m_floatingTab.reset();
 
     resetOldPositions();
     startAnimation(ANI_ADDING_TAB, ANI_ADDING_TAB_TICKS);
diff --git a/src/app/util/expand_cel_canvas.cpp b/src/app/util/expand_cel_canvas.cpp
index 45e0b3959..a2165bab5 100644
--- a/src/app/util/expand_cel_canvas.cpp
+++ b/src/app/util/expand_cel_canvas.cpp
@@ -164,7 +164,7 @@ void ExpandCelCanvas::commit()
 
       // Copy the destination to the cel image.
       m_transaction.execute(new cmd::CopyRegion(
-          m_celImage, m_dstImage, m_validDstRegion, dx, dy));
+          m_celImage.get(), m_dstImage, m_validDstRegion, dx, dy));
     }
     // If the size of both images are different, we have to
     // replace the entire image.
@@ -252,7 +252,7 @@ void ExpandCelCanvas::validateSourceCanvas(const gfx::Region& rgn)
       fill_rect(m_srcImage, rc, m_srcImage->maskColor());
 
     for (const auto& rc : rgnToValidate)
-      m_srcImage->copy(m_celImage,
+      m_srcImage->copy(m_celImage.get(),
         gfx::Clip(rc.x, rc.y,
           rc.x+m_bounds.x-m_origCelPos.x,
           rc.y+m_bounds.y-m_origCelPos.y, rc.w, rc.h));
@@ -276,7 +276,7 @@ void ExpandCelCanvas::validateDestCanvas(const gfx::Region& rgn)
     src_y = m_bounds.y;
   }
   else {
-    src = m_celImage;
+    src = m_celImage.get();
     src_x = m_origCelPos.x;
     src_y = m_origCelPos.y;
   }
diff --git a/src/app/util/pic_file.cpp b/src/app/util/pic_file.cpp
index 4c82d3898..0da42d35b 100644
--- a/src/app/util/pic_file.cpp
+++ b/src/app/util/pic_file.cpp
@@ -38,7 +38,8 @@ Image* load_pic_file(const char* filename, int* x, int* y, Palette** palette)
   int byte;
   int bpp;
 
-  base::FileHandle f(base::open_file_with_exception(filename, "rb"));
+  base::FileHandle handle(base::open_file_with_exception(filename, "rb"));
+  FILE* f = handle.get();
 
   // Animator format?
   magic = base::fgetw(f);
@@ -83,8 +84,9 @@ Image* load_pic_file(const char* filename, int* x, int* y, Palette** palette)
   }
 
   // rewind
-  f.reset(NULL);
-  f = base::open_file_with_exception(filename, "rb");
+  handle.reset();
+  handle = base::open_file_with_exception(filename, "rb");
+  f = handle.get();
 
   // read a PIC/MSK Animator Pro file
   size = base::fgetl(f);        // file size
@@ -172,7 +174,8 @@ int save_pic_file(const char *filename, int x, int y, const Palette* palette, co
   if ((bpp == 8) && (!palette))
     return -1;
 
-  base::FileHandle f(base::open_file_with_exception(filename, "wb"));
+  base::FileHandle handle(base::open_file_with_exception(filename, "wb"));
+  FILE* f = handle.get();
 
   size = 64;
   // Bit-per-pixel image data block
diff --git a/src/app/widget_loader.cpp b/src/app/widget_loader.cpp
index a3c4e14aa..f5caa8e52 100644
--- a/src/app/widget_loader.cpp
+++ b/src/app/widget_loader.cpp
@@ -89,7 +89,7 @@ Widget* WidgetLoader::loadWidgetFromXmlFile(
   m_tooltipManager = NULL;
 
   XmlDocumentRef doc(open_xml(xmlFilename));
-  TiXmlHandle handle(doc);
+  TiXmlHandle handle(doc.get());
 
   // Search the requested widget.
   TiXmlElement* xmlElement = handle
diff --git a/src/app/xml_document.cpp b/src/app/xml_document.cpp
index deb625c6e..85c11715b 100644
--- a/src/app/xml_document.cpp
+++ b/src/app/xml_document.cpp
@@ -29,8 +29,8 @@ XmlDocumentRef open_xml(const std::string& filename)
   // Try to load the XML file
   XmlDocumentRef doc(new TiXmlDocument());
   doc->SetValue(filename.c_str());
-  if (!doc->LoadFile(file))
-    throw XmlException(doc);
+  if (!doc->LoadFile(file.get()))
+    throw XmlException(doc.get());
 
   return doc;
 }
@@ -41,8 +41,8 @@ void save_xml(XmlDocumentRef doc, const std::string& filename)
   if (!file)
     throw Exception("Error loading file: " + filename);
 
-  if (!doc->SaveFile(file))
-    throw XmlException(doc);
+  if (!doc->SaveFile(file.get()))
+    throw XmlException(doc.get());
 }
 
 bool bool_attr_is_true(const TiXmlElement* elem, const char* attrName)
diff --git a/src/base/shared_ptr.h b/src/base/shared_ptr.h
index 486004dd9..1dc3f89d9 100644
--- a/src/base/shared_ptr.h
+++ b/src/base/shared_ptr.h
@@ -1,5 +1,5 @@
 // Aseprite Base Library
-// Copyright (c) 2001-2013 David Capello
+// Copyright (c) 2001-2013, 2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -211,7 +211,7 @@ public:
   T* get() const { return m_ptr; }
   T& operator*() const { return *m_ptr; }
   T* operator->() const { return m_ptr; }
-  operator T*() const { return m_ptr; }
+  explicit operator bool() const { return (m_ptr != nullptr); }
 
   long use_count() const { return (m_refCount ? m_refCount->use_count(): 0); }
   bool unique() const { return use_count() == 1; }
diff --git a/src/doc/cel_data_io.cpp b/src/doc/cel_data_io.cpp
index dbfbff86f..14e72dc0b 100644
--- a/src/doc/cel_data_io.cpp
+++ b/src/doc/cel_data_io.cpp
@@ -22,7 +22,7 @@ namespace doc {
 using namespace base::serialization;
 using namespace base::serialization::little_endian;
 
-void write_celdata(std::ostream& os, CelData* celdata)
+void write_celdata(std::ostream& os, const CelData* celdata)
 {
   write32(os, celdata->id());
   write16(os, (int16_t)celdata->position().x);
diff --git a/src/doc/cel_data_io.h b/src/doc/cel_data_io.h
index 4ec84b50a..8197e20e7 100644
--- a/src/doc/cel_data_io.h
+++ b/src/doc/cel_data_io.h
@@ -15,7 +15,7 @@ namespace doc {
   class CelData;
   class SubObjectsIO;
 
-  void write_celdata(std::ostream& os, CelData* cel);
+  void write_celdata(std::ostream& os, const CelData* cel);
   CelData* read_celdata(std::istream& is, SubObjectsIO* subObjects);
 
 } // namespace doc
diff --git a/src/doc/cel_io.cpp b/src/doc/cel_io.cpp
index f4ce40a91..09e192ea2 100644
--- a/src/doc/cel_io.cpp
+++ b/src/doc/cel_io.cpp
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -22,7 +22,7 @@ namespace doc {
 using namespace base::serialization;
 using namespace base::serialization::little_endian;
 
-void write_cel(std::ostream& os, Cel* cel)
+void write_cel(std::ostream& os, const Cel* cel)
 {
   write32(os, cel->id());
   write16(os, cel->frame());
diff --git a/src/doc/cel_io.h b/src/doc/cel_io.h
index 3a10db5e9..66069bebd 100644
--- a/src/doc/cel_io.h
+++ b/src/doc/cel_io.h
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -15,7 +15,7 @@ namespace doc {
   class Cel;
   class SubObjectsIO;
 
-  void write_cel(std::ostream& os, Cel* cel);
+  void write_cel(std::ostream& os, const Cel* cel);
   Cel* read_cel(std::istream& is, SubObjectsIO* subObjects);
 
 } // namespace doc
diff --git a/src/doc/frame_tag_io.cpp b/src/doc/frame_tag_io.cpp
index cc8b5e990..3410951b3 100644
--- a/src/doc/frame_tag_io.cpp
+++ b/src/doc/frame_tag_io.cpp
@@ -22,7 +22,7 @@ namespace doc {
 using namespace base::serialization;
 using namespace base::serialization::little_endian;
 
-void write_frame_tag(std::ostream& os, FrameTag* tag)
+void write_frame_tag(std::ostream& os, const FrameTag* tag)
 {
   std::string name = tag->name();
 
diff --git a/src/doc/frame_tag_io.h b/src/doc/frame_tag_io.h
index 7db131626..76e39e1a7 100644
--- a/src/doc/frame_tag_io.h
+++ b/src/doc/frame_tag_io.h
@@ -14,7 +14,7 @@ namespace doc {
 
   class FrameTag;
 
-  void write_frame_tag(std::ostream& os, FrameTag* tag);
+  void write_frame_tag(std::ostream& os, const FrameTag* tag);
   FrameTag* read_frame_tag(std::istream& is);
 
 } // namespace doc
diff --git a/src/doc/image_io.cpp b/src/doc/image_io.cpp
index 63330505d..f88d5e744 100644
--- a/src/doc/image_io.cpp
+++ b/src/doc/image_io.cpp
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -33,7 +33,7 @@ using namespace base::serialization::little_endian;
 //        BYTE[2]       for Grayscale images, or
 //        BYTE          for Indexed images
 
-void write_image(std::ostream& os, Image* image)
+void write_image(std::ostream& os, const Image* image)
 {
   write32(os, image->id());
   write8(os, image->pixelFormat());    // Pixel format
diff --git a/src/doc/image_io.h b/src/doc/image_io.h
index 36bd2083c..c814baab7 100644
--- a/src/doc/image_io.h
+++ b/src/doc/image_io.h
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -14,7 +14,7 @@ namespace doc {
 
   class Image;
 
-  void write_image(std::ostream& os, Image* image);
+  void write_image(std::ostream& os, const Image* image);
   Image* read_image(std::istream& is);
 
 } // namespace doc
diff --git a/src/doc/layer_io.cpp b/src/doc/layer_io.cpp
index 9e6eeda97..c697e55be 100644
--- a/src/doc/layer_io.cpp
+++ b/src/doc/layer_io.cpp
@@ -33,7 +33,7 @@ using namespace base::serialization::little_endian;
 
 // Serialized Layer data:
 
-void write_layer(std::ostream& os, Layer* layer)
+void write_layer(std::ostream& os, const Layer* layer)
 {
   std::string name = layer->name();
 
@@ -46,8 +46,8 @@ void write_layer(std::ostream& os, Layer* layer)
   switch (layer->type()) {
 
     case ObjectType::LayerImage: {
-      CelIterator it, begin = static_cast<LayerImage*>(layer)->getCelBegin();
-      CelIterator end = static_cast<LayerImage*>(layer)->getCelEnd();
+      CelConstIterator it, begin = static_cast<const LayerImage*>(layer)->getCelBegin();
+      CelConstIterator end = static_cast<const LayerImage*>(layer)->getCelEnd();
 
       // Images
       int images = 0;
@@ -71,24 +71,24 @@ void write_layer(std::ostream& os, Layer* layer)
       for (it=begin; it != end; ++it) {
         Cel* cel = *it;
         if (!cel->link())
-          write_celdata(os, cel->dataRef());
+          write_celdata(os, cel->dataRef().get());
       }
 
       // Cels
-      write16(os, static_cast<LayerImage*>(layer)->getCelsCount());
+      write16(os, static_cast<const LayerImage*>(layer)->getCelsCount());
       for (it=begin; it != end; ++it) {
-        Cel* cel = *it;
+        const Cel* cel = *it;
         write_cel(os, cel);
       }
       break;
     }
 
     case ObjectType::LayerFolder: {
-      LayerIterator it = static_cast<LayerFolder*>(layer)->getLayerBegin();
-      LayerIterator end = static_cast<LayerFolder*>(layer)->getLayerEnd();
+      LayerConstIterator it = static_cast<const LayerFolder*>(layer)->getLayerBegin();
+      LayerConstIterator end = static_cast<const LayerFolder*>(layer)->getLayerEnd();
 
       // Number of sub-layers
-      write16(os, static_cast<LayerFolder*>(layer)->getLayersCount());
+      write16(os, static_cast<const LayerFolder*>(layer)->getLayersCount());
 
       for (; it != end; ++it)
         write_layer(os, *it);
diff --git a/src/doc/layer_io.h b/src/doc/layer_io.h
index afe9a1238..16edfaaeb 100644
--- a/src/doc/layer_io.h
+++ b/src/doc/layer_io.h
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -22,7 +22,7 @@ namespace doc {
     InvalidLayerType(const char* msg) throw() : base::Exception(msg) { }
   };
 
-  void write_layer(std::ostream& os, Layer* layer);
+  void write_layer(std::ostream& os, const Layer* layer);
   Layer* read_layer(std::istream& is, SubObjectsIO* subObjects);
 
 } // namespace doc
diff --git a/src/doc/mask.cpp b/src/doc/mask.cpp
index 623136a03..c70897d51 100644
--- a/src/doc/mask.cpp
+++ b/src/doc/mask.cpp
@@ -74,7 +74,7 @@ bool Mask::isRectangular() const
   if (!m_bitmap)
     return false;
 
-  LockImageBits<BitmapTraits> bits(m_bitmap);
+  LockImageBits<BitmapTraits> bits(m_bitmap.get());
   LockImageBits<BitmapTraits>::iterator it = bits.begin(), end = bits.end();
 
   for (; it != end; ++it) {
@@ -95,7 +95,7 @@ void Mask::copyFrom(const Mask* sourceMask)
     add(sourceMask->bounds());
 
     // And copy the "mask" bitmap
-    copy_image(m_bitmap, sourceMask->m_bitmap);
+    copy_image(m_bitmap.get(), sourceMask->m_bitmap.get());
   }
 }
 
@@ -106,7 +106,7 @@ void Mask::offsetOrigin(int dx, int dy)
 
 void Mask::clear()
 {
-  m_bitmap.reset(nullptr);
+  m_bitmap.reset();
   m_bounds = gfx::Rect(0, 0, 0, 0);
 }
 
@@ -115,7 +115,7 @@ void Mask::invert()
   if (!m_bitmap)
     return;
 
-  LockImageBits<BitmapTraits> bits(m_bitmap);
+  LockImageBits<BitmapTraits> bits(m_bitmap.get());
   LockImageBits<BitmapTraits>::iterator it = bits.begin(), end = bits.end();
 
   for (; it != end; ++it)
@@ -129,7 +129,7 @@ void Mask::replace(const gfx::Rect& bounds)
   m_bounds = bounds;
 
   m_bitmap.reset(Image::create(IMAGE_BITMAP, bounds.w, bounds.h, m_buffer));
-  clear_image(m_bitmap, 1);
+  clear_image(m_bitmap.get(), 1);
 }
 
 void Mask::add(const gfx::Rect& bounds)
@@ -137,7 +137,7 @@ void Mask::add(const gfx::Rect& bounds)
   if (m_freeze_count == 0)
     reserve(bounds);
 
-  fill_rect(m_bitmap,
+  fill_rect(m_bitmap.get(),
     bounds.x-m_bounds.x,
     bounds.y-m_bounds.y,
     bounds.x-m_bounds.x+bounds.w-1,
@@ -149,7 +149,7 @@ void Mask::subtract(const gfx::Rect& bounds)
   if (!m_bitmap)
     return;
 
-  fill_rect(m_bitmap,
+  fill_rect(m_bitmap.get(),
     bounds.x-m_bounds.x,
     bounds.y-m_bounds.y,
     bounds.x-m_bounds.x+bounds.w-1,
@@ -168,7 +168,7 @@ void Mask::intersect(const gfx::Rect& bounds)
   Image* image = NULL;
 
   if (!newBounds.isEmpty()) {
-    image = crop_image(m_bitmap,
+    image = crop_image(m_bitmap.get(),
       newBounds.x-m_bounds.x,
       newBounds.y-m_bounds.y,
       newBounds.w,
@@ -185,7 +185,7 @@ void Mask::byColor(const Image *src, int color, int fuzziness)
 {
   replace(src->bounds());
 
-  Image* dst = m_bitmap;
+  Image* dst = m_bitmap.get();
 
   switch (src->pixelFormat()) {
 
@@ -358,13 +358,13 @@ void Mask::reserve(const gfx::Rect& bounds)
   if (!m_bitmap) {
     m_bounds = bounds;
     m_bitmap.reset(Image::create(IMAGE_BITMAP, bounds.w, bounds.h, m_buffer));
-    clear_image(m_bitmap, 0);
+    clear_image(m_bitmap.get(), 0);
   }
   else {
     gfx::Rect newBounds = m_bounds.createUnion(bounds);
 
     if (m_bounds != newBounds) {
-      Image* image = crop_image(m_bitmap,
+      Image* image = crop_image(m_bitmap.get(),
         newBounds.x-m_bounds.x,
         newBounds.y-m_bounds.y,
         newBounds.w,
@@ -428,7 +428,7 @@ void Mask::shrink()
     m_bounds.w = x2 - x1 + 1;
     m_bounds.h = y2 - y1 + 1;
 
-    Image* image = crop_image(m_bitmap, m_bounds.x-u, m_bounds.y-v, m_bounds.w, m_bounds.h, 0);
+    Image* image = crop_image(m_bitmap.get(), m_bounds.x-u, m_bounds.y-v, m_bounds.w, m_bounds.h, 0);
     m_bitmap.reset(image);
   }
 
diff --git a/src/doc/mask.h b/src/doc/mask.h
index bdab19c16..be542b0c0 100644
--- a/src/doc/mask.h
+++ b/src/doc/mask.h
@@ -31,8 +31,8 @@ namespace doc {
     void setName(const char *name);
     const std::string& name() const { return m_name; }
 
-    const Image* bitmap() const { return m_bitmap; }
-    Image* bitmap() { return m_bitmap; }
+    const Image* bitmap() const { return m_bitmap.get(); }
+    Image* bitmap() { return m_bitmap.get(); }
 
     // Returns true if the mask is completely empty (i.e. nothing
     // selected)
@@ -42,10 +42,10 @@ namespace doc {
 
     // Returns true if the point is inside the mask
     bool containsPoint(int u, int v) const {
-      return (m_bitmap &&
+      return (m_bitmap.get() &&
               u >= m_bounds.x && u < m_bounds.x+m_bounds.w &&
               v >= m_bounds.y && v < m_bounds.y+m_bounds.h &&
-              get_pixel(m_bitmap, u-m_bounds.x, v-m_bounds.y));
+              get_pixel(m_bitmap.get(), u-m_bounds.x, v-m_bounds.y));
     }
 
     const gfx::Rect& bounds() const { return m_bounds; }
diff --git a/src/doc/mask_io.cpp b/src/doc/mask_io.cpp
index 1a074a8ad..7d5323fad 100644
--- a/src/doc/mask_io.cpp
+++ b/src/doc/mask_io.cpp
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -29,7 +29,7 @@ using namespace base::serialization::little_endian;
 //       BYTE           8 pixels of the mask
 //       BYTE           for Indexed images
 
-void write_mask(std::ostream& os, Mask* mask)
+void write_mask(std::ostream& os, const Mask* mask)
 {
   const gfx::Rect& bounds = mask->bounds();
 
diff --git a/src/doc/mask_io.h b/src/doc/mask_io.h
index 1aee78f37..1e6cdb378 100644
--- a/src/doc/mask_io.h
+++ b/src/doc/mask_io.h
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -14,7 +14,7 @@ namespace doc {
 
   class Mask;
 
-  void write_mask(std::ostream& os, Mask* mask);
+  void write_mask(std::ostream& os, const Mask* mask);
   Mask* read_mask(std::istream& is);
 
 } // namespace doc
diff --git a/src/doc/palette_io.cpp b/src/doc/palette_io.cpp
index 7f9748b2c..f5e03fa44 100644
--- a/src/doc/palette_io.cpp
+++ b/src/doc/palette_io.cpp
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -28,7 +28,7 @@ using namespace base::serialization::little_endian;
 //   for each color     ("ncolors" times)
 //     DWORD            _rgba color
 
-void write_palette(std::ostream& os, Palette* palette)
+void write_palette(std::ostream& os, const Palette* palette)
 {
   write16(os, palette->frame()); // Frame
   write16(os, palette->size());  // Number of colors
diff --git a/src/doc/palette_io.h b/src/doc/palette_io.h
index 2530cdc33..3e137600e 100644
--- a/src/doc/palette_io.h
+++ b/src/doc/palette_io.h
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -14,7 +14,7 @@ namespace doc {
 
   class Palette;
 
-  void write_palette(std::ostream& os, Palette* palette);
+  void write_palette(std::ostream& os, const Palette* palette);
   Palette* read_palette(std::istream& is);
 
 } // namespace doc
diff --git a/src/doc/sprite.cpp b/src/doc/sprite.cpp
index e6dca363b..2e903ff17 100644
--- a/src/doc/sprite.cpp
+++ b/src/doc/sprite.cpp
@@ -105,7 +105,7 @@ Sprite* Sprite::createBasicSprite(doc::PixelFormat format, int width, int height
 
   // Create the main image.
   doc::ImageRef image(doc::Image::create(format, width, height));
-  doc::clear_image(image, 0);
+  doc::clear_image(image.get(), 0);
 
   // Create the first transparent layer.
   {
diff --git a/src/filters/convolution_matrix_filter.cpp b/src/filters/convolution_matrix_filter.cpp
index 46a55aa26..0af3a7e15 100644
--- a/src/filters/convolution_matrix_filter.cpp
+++ b/src/filters/convolution_matrix_filter.cpp
@@ -155,7 +155,7 @@ void ConvolutionMatrixFilter::applyToRgba(FilterManager* filterMgr)
       continue;
     }
 
-    delegate.reset(m_matrix);
+    delegate.reset(m_matrix.get());
     get_neighboring_pixels<RgbTraits>(src, x, y,
                                       m_matrix->getWidth(),
                                       m_matrix->getHeight(),
@@ -222,7 +222,7 @@ void ConvolutionMatrixFilter::applyToGrayscale(FilterManager* filterMgr)
       continue;
     }
 
-    delegate.reset(m_matrix);
+    delegate.reset(m_matrix.get());
     get_neighboring_pixels<GrayscaleTraits>(src, x, y,
                                             m_matrix->getWidth(),
                                             m_matrix->getHeight(),
@@ -277,7 +277,7 @@ void ConvolutionMatrixFilter::applyToIndexed(FilterManager* filterMgr)
       continue;
     }
 
-    delegate.reset(m_matrix);
+    delegate.reset(m_matrix.get());
     get_neighboring_pixels<IndexedTraits>(src, x, y,
                                           m_matrix->getWidth(),
                                           m_matrix->getHeight(),
diff --git a/src/gen/gen.cpp b/src/gen/gen.cpp
index ca31e4bbd..557e9261c 100644
--- a/src/gen/gen.cpp
+++ b/src/gen/gen.cpp
@@ -35,7 +35,7 @@ static void run(int argc, const char* argv[])
     base::FileHandle inputFile(base::open_file(inputFilename, "rb"));
     doc = new TiXmlDocument();
     doc->SetValue(inputFilename.c_str());
-    if (!doc->LoadFile(inputFile))
+    if (!doc->LoadFile(inputFile.get()))
       throw std::runtime_error("invalid input file");
   }
 
diff --git a/src/render/quantization.cpp b/src/render/quantization.cpp
index c7631141d..5d803f3be 100644
--- a/src/render/quantization.cpp
+++ b/src/render/quantization.cpp
@@ -1,5 +1,5 @@
 // Aseprite Render Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -61,7 +61,7 @@ Palette* create_palette_from_rgb(
   ImageRef flat_image(Image::create(sprite->pixelFormat(),
       sprite->width(), sprite->height()));
 
-  render::Render().renderSprite(flat_image, sprite, frameNumber);
+  render::Render().renderSprite(flat_image.get(), sprite, frameNumber);
 
   // Create an array of images
   std::vector<Image*> image_array;
@@ -76,7 +76,7 @@ Palette* create_palette_from_rgb(
       image_array.push_back(image);
     }
   }
-  image_array.push_back(flat_image);
+  image_array.push_back(flat_image.get());
 
   // Generate an optimized palette for all images
   create_palette_from_images(image_array, palette, has_background_layer);
diff --git a/src/ui/widget.cpp b/src/ui/widget.cpp
index 3fa11d186..c4b47e994 100644
--- a/src/ui/widget.cpp
+++ b/src/ui/widget.cpp
@@ -1326,7 +1326,7 @@ bool Widget::onProcessMessage(Message* msg)
       ASSERT(ptmsg->rect().h > 0);
 
       GraphicsPtr graphics = getGraphics(toClient(ptmsg->rect()));
-      return paintEvent(graphics);
+      return paintEvent(graphics.get());
     }
 
     case kKeyDownMessage: