diff --git a/iframe_filter.module b/iframe_filter.module
index f869604..b5b6908 100644
--- a/iframe_filter.module
+++ b/iframe_filter.module
@@ -69,7 +69,7 @@ function iframe_filter_parse($text){
   $destination_file = $files_dir . '/' . $filename;
 
   // Look for a width= and height= attributes in this text (most obvious).
-  if (preg_match('/width[ ]*=[ ]*"(\d+)"/', $text, $matches)) {
+  if (preg_match('/width[ ]*=[ ]*"(\d+[%]?)"/', $text, $matches)) {
     $width = $matches[1];
   }
   if (preg_match('/height[ ]*=[ ]*"(\d+)"/', $text, $matches)) {