diff --git a/includes/common.inc b/includes/common.inc
index 36c44e1..f50a7af 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -3774,7 +3774,7 @@ function _drupal_load_stylesheet($matches) {
   // Alter all internal url() paths. Leave external paths alone. We don't need
   // to normalize absolute paths here (i.e. remove folder/... segments) because
   // that will be done later.
-  return preg_replace('/url\(\s*([\'"]?)(?![a-z]+:|\/+)/i', 'url(\1'. $directory, $file);
+  return preg_replace('/url\(\s*([\'"]?)(?![a-z]+:|\/+)([^\'")]+)([\'"]?)\s*\)/i', 'url(\1' . $directory . '\2\3)', $file);
 }
 
 /**