diff --git a/lib/exe/css.php b/lib/exe/css.php
index 1e662c64a77c9d57dc654914dd117d4fea850c6f..768c8eda486328feaa222f8fcbc1621b8aaab1ca 100644
--- a/lib/exe/css.php
+++ b/lib/exe/css.php
@@ -314,7 +314,7 @@ function css_datauri($match){
         $data = base64_encode(file_get_contents($local));
     }
     if($data){
-        $url = 'data:image/'.$ext.';base64,'.$data;
+        $url = '\'data:image/'.$ext.';base64,'.$data.'\'';
     }else{
         $url = $base.$url;
     }