diff --git a/theme/default/display.css b/theme/default/display.css
index 91ce3294c0..0ad6657292 100644
--- a/theme/default/display.css
+++ b/theme/default/display.css
@@ -245,7 +245,7 @@ line-height:18px;
 
 #wrap p#nudge_response {
 padding-left:20px;
-background:transparent url(icon_checkmark.png) 0 1px no-repeat;
+background:transparent url(icon_checkmark.gif) 0 1px no-repeat;
 line-height:18px;
 font-size:14px;
 }
diff --git a/theme/default/icon_checkmark.gif b/theme/default/icon_checkmark.gif
new file mode 100644
index 0000000000..98776df7b5
Binary files /dev/null and b/theme/default/icon_checkmark.gif differ
diff --git a/theme/default/icon_checkmark.png b/theme/default/icon_checkmark.png
deleted file mode 100644
index 818e3b5f8b..0000000000
Binary files a/theme/default/icon_checkmark.png and /dev/null differ