Index: wp-admin/includes/media.php
===================================================================
--- wp-admin/includes/media.php	(revision 17487)
+++ wp-admin/includes/media.php	(working copy)
@@ -563,7 +563,7 @@
 
 		// Set variables for storage
 		// fix file filename for query strings
-		preg_match('/[^\?]+\.(jpg|JPG|jpe|JPE|jpeg|JPEG|gif|GIF|png|PNG)/', $file, $matches);
+		preg_match('/[^\?]+\.(jpe?g|jpe|gif|png)\b/i', $file, $matches);
 		$file_array['name'] = basename($matches[0]);
 		$file_array['tmp_name'] = $tmp;