diff --git a/src/util/msk_file.cpp b/src/util/msk_file.cpp
index 4826e4242..24bef1e69 100644
--- a/src/util/msk_file.cpp
+++ b/src/util/msk_file.cpp
@@ -94,7 +94,7 @@ Mask *load_msk_file(const char *filename)
 }
 
 /* saves an Animator Pro MSK file (really a PIC file) */
-int save_msk_file(Mask *mask, const char *filename)
+int save_msk_file(const Mask *mask, const char *filename)
 {
   if (mask->bitmap)
     return save_pic_file(filename, mask->x, mask->y, NULL, mask->bitmap);
diff --git a/src/util/msk_file.h b/src/util/msk_file.h
index f32790c76..c1d03514b 100644
--- a/src/util/msk_file.h
+++ b/src/util/msk_file.h
@@ -22,7 +22,7 @@
 class Mask;
 
 Mask* load_msk_file(const char* filename);
-int save_msk_file(Mask* mask, const char* filename);
+int save_msk_file(const Mask* mask, const char* filename);
 
 #endif
 
diff --git a/src/util/pic_file.cpp b/src/util/pic_file.cpp
index ff9bc53cb..e3f674a4f 100644
--- a/src/util/pic_file.cpp
+++ b/src/util/pic_file.cpp
@@ -173,10 +173,11 @@ Image *load_pic_file(const char *filename, int *x, int *y, RGB *palette)
 }
 
 /* saves an Animator Pro PIC file */
-int save_pic_file(const char *filename, int x, int y, RGB *palette, Image *image)
+int save_pic_file(const char *filename, int x, int y,
+		  const RGB* palette, const Image* image)
 {
   int c, u, v, bpp, size, byte;
-  PACKFILE *f;
+  PACKFILE* f;
 
   if (image->imgtype == IMAGE_INDEXED)
     bpp = 8;
diff --git a/src/util/pic_file.h b/src/util/pic_file.h
index 2f798e95c..d2189cb9a 100644
--- a/src/util/pic_file.h
+++ b/src/util/pic_file.h
@@ -23,10 +23,10 @@
 
 class Image;
 
-Image* load_pic_file(const char *filename, int *x, int *y,
-		     struct RGB *palette);
+Image* load_pic_file(const char* filename, int *x, int *y,
+		     RGB* palette);
 
-int save_pic_file(const char *filename, int x, int y,
-		  struct RGB *palette, Image* image);
+int save_pic_file(const char* filename, int x, int y,
+		  const RGB* palette, const Image* image);
 
 #endif