diff --git a/src/CSS.php b/src/CSS.php
index 1b354ad..ab32883 100644
--- a/src/CSS.php
+++ b/src/CSS.php
@@ -252,7 +252,7 @@ protected function combineImports($source, $content, $parents)
      */
     protected function importFiles($source, $content)
     {
-        $regex = '/url\((["\']?)(.+?)\\1\)/i';
+	    $regex = '/url\((["\']?)([^"\']+?)\\1\)/i';
         if ($this->importExtensions && preg_match_all($regex, $content, $matches, PREG_SET_ORDER)) {
             $search = array();
             $replace = array();