diff --git a/lib/common.js b/lib/common.js
index cbe5b550d..82b88e90d 100644
--- a/lib/common.js
+++ b/lib/common.js
@@ -308,11 +308,9 @@ function percentEncode(str) {
 }
 
 function matchStringOrRegexp(target, pattern) {
-  if (pattern instanceof RegExp) {
-    return target.toString().match(pattern);
-  } else {
-    return target.toString() === pattern;
-  }
+  var str = target && target.toString ? target.toString() : target;
+
+  return pattern instanceof RegExp  ? str.match(pattern) : str === pattern;
 }
 
 // return [newKey, newValue]