diff --git a/src/app/file/ase_format.cpp b/src/app/file/ase_format.cpp
index 3f130f2a5..de48b91fc 100644
--- a/src/app/file/ase_format.cpp
+++ b/src/app/file/ase_format.cpp
@@ -144,7 +144,8 @@ class AseFormat : public FileFormat {
       FILE_SUPPORT_FRAMES |
       FILE_SUPPORT_PALETTES |
       FILE_SUPPORT_FRAME_TAGS |
-      FILE_SUPPORT_BIG_PALETTES;
+      FILE_SUPPORT_BIG_PALETTES |
+      FILE_SUPPORT_PALETTE_WITH_ALPHA;
   }
 
   bool onLoad(FileOp* fop) override;
diff --git a/src/app/file/file.cpp b/src/app/file/file.cpp
index 3316b7df4..9612277ed 100644
--- a/src/app/file/file.cpp
+++ b/src/app/file/file.cpp
@@ -332,6 +332,22 @@ FileOp* fop_to_save_document(const Context* context, const Document* document,
     }
   }
 
+  // Palette with alpha
+  if (!fop->format->support(FILE_SUPPORT_PALETTE_WITH_ALPHA)) {
+    bool done = false;
+    for (Palette* pal : fop->document->sprite()->getPalettes()) {
+      for (int c=0; c<pal->size(); ++c) {
+        if (rgba_geta(pal->getEntry(c)) < 255) {
+          warnings += "<<- Palette with alpha channel";
+          done = true;
+          break;
+        }
+      }
+      if (done)
+        break;
+    }
+  }
+
   // Show the confirmation alert
   if (!warnings.empty()) {
     // Interative
diff --git a/src/app/file/file_format.h b/src/app/file/file_format.h
index 9485020c5..e6f179079 100644
--- a/src/app/file/file_format.h
+++ b/src/app/file/file_format.h
@@ -27,6 +27,7 @@
 #define FILE_SUPPORT_GET_FORMAT_OPTIONS 0x00000800
 #define FILE_SUPPORT_FRAME_TAGS         0x00001000
 #define FILE_SUPPORT_BIG_PALETTES       0x00002000 // Palettes w/more than 256 colors
+#define FILE_SUPPORT_PALETTE_WITH_ALPHA 0x00004000
 
 namespace app {