diff --git a/lib/ConnectSequence.js b/lib/ConnectSequence.js
index 9572ca3..8efaf5f 100644
--- a/lib/ConnectSequence.js
+++ b/lib/ConnectSequence.js
@@ -234,9 +234,7 @@ function appendListIf (filter, middlewares) {
  * @returns {Boolean}
  */
 function isErrorHandler (cb) {
-  var str = cb.toString()
-  var args = str.split('(')[1].split(')')[0].split(',')
-  return args.length === 4
+  return cb.length === 4
 }
 
 /**