diff --git a/docs/ase-file-specs.md b/docs/ase-file-specs.md
index 8442ca9bb..18ff5b247 100644
--- a/docs/ase-file-specs.md
+++ b/docs/ase-file-specs.md
@@ -126,9 +126,12 @@ at least.
 
 ### Old palette chunk (0x0004)
 
-Ignore this chunk if you find the new palette chunk (0x2019) Aseprite
-v1.1 saves both chunks 0x0004 and 0x2019 just for backward
-compatibility.
+Ignore this chunk if you find the new palette chunk (0x2019). Aseprite
+v1.1 saves both chunks (0x0004 and 0x2019) just for backward
+compatibility. Aseprite v1.3.5 writes this chunk if the palette
+doesn't have alpha channel and contains 256 colors or less (because
+this chunk is smaller), in other case the new palette chunk (0x2019)
+will be used (and the old one is not saved anymore).
 
     WORD        Number of packets
     + For each packet
diff --git a/src/app/file/ase_format.cpp b/src/app/file/ase_format.cpp
index 8ca37ff26..20fd02588 100644
--- a/src/app/file/ase_format.cpp
+++ b/src/app/file/ase_format.cpp
@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2023  Igara Studio S.A.
+// Copyright (C) 2018-2024  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -355,7 +355,7 @@ bool AseFormat::onSave(FileOp* fop)
 
   bool require_new_palette_chunk = false;
   for (Palette* pal : sprite->getPalettes()) {
-    if (pal->size() != 256 || pal->hasAlpha()) {
+    if (pal->size() > 256 || pal->hasAlpha()) {
       require_new_palette_chunk = true;
       break;
     }
@@ -393,9 +393,12 @@ bool AseFormat::onSave(FileOp* fop)
         ase_file_write_palette_chunk(f, &frame_header,
                                      pal, palFrom, palTo);
       }
-
-      // Write color chunk for backward compatibility only
-      ase_file_write_color2_chunk(f, &frame_header, pal);
+      else {
+        // Use old color chunk only when the palette has 256 or less
+        // colors, and we don't need the alpha channel (as this chunk
+        // is smaller than the new palette chunk).
+        ase_file_write_color2_chunk(f, &frame_header, pal);
+      }
     }
 
     // Write extra chunks in the first frame
@@ -676,6 +679,7 @@ static void ase_file_write_color2_chunk(FILE* f, dio::AsepriteFrameHeader* frame
 
   // First packet
   fputc(0, f);                                   // skip 0 colors
+  ASSERT(pal->size() <= 256);                    // For >256 we use the palette chunk
   fputc(pal->size() == 256 ? 0: pal->size(), f); // number of colors
   for (c=0; c<pal->size(); c++) {
     color = pal->getEntry(c);