diff --git a/PIL/ImagePalette.py b/PIL/ImagePalette.py
index d5b9d04eb..59886827a 100644
--- a/PIL/ImagePalette.py
+++ b/PIL/ImagePalette.py
@@ -101,8 +101,11 @@ class ImagePalette:
         fp.write("# Mode: %s\n" % self.mode)
         for i in range(256):
             fp.write("%d" % i)
-            for j in range(i, len(self.palette), 256):
-                fp.write(" %d" % self.palette[j])
+            for j in range(i*len(self.mode), (i+1)*len(self.mode)):
+                try:
+                    fp.write(" %d" % self.palette[j])
+                except IndexError:
+                    fp.write(" 0")
             fp.write("\n")
         fp.close()