Index: imagecache_actions/watermark.inc
===================================================================
--- imagecache_actions/watermark.inc	(revision 2813)
+++ imagecache_actions/watermark.inc	(working copy)
@@ -44,8 +44,11 @@
       $transparent = imagecolorallocatealpha($return_img, $transparent['red'], $transparent['green'], $transparent['blue'], $transparent['alpha']);
       imagecolortransparent($return_img, $transparent);
     }
+    
     $watermark_transparent_ix = imagecolortransparent($watermark_img_obj);
-    if ($watermark_transparent_ix >= 0) {
+    $palletsize = imagecolorstotal($watermark_img_obj);
+
+    if ($watermark_transparent_ix >= 0 && $watermark_transparent_ix < $palletsize) {
       $watermark_transparent = imagecolorsforindex($watermark_img_obj, $watermark_transparent_ix);
     }