diff --git a/src/static/js/pad.js b/src/static/js/pad.js
index 504bc21e4..9a42bccce 100644
--- a/src/static/js/pad.js
+++ b/src/static/js/pad.js
@@ -463,7 +463,7 @@ var pad = {
     {
       try
       {
-        doc.execCommand("BackgroundImageCache", false, true);
+        document.execCommand("BackgroundImageCache", false, true);
       }
       catch (e)
       {}