diff --git a/remix-simulator/src/provider.js b/remix-simulator/src/provider.js
index 939b75afa2..1f4e5d9b80 100644
--- a/remix-simulator/src/provider.js
+++ b/remix-simulator/src/provider.js
@@ -36,8 +36,8 @@ Provider.prototype.sendAsync = function (payload, callback) {
   callback(new Error('unknown method ' + payload.method))
 }
 
-Provider.prototype.send = function(payload, callback) {
-  this.sendAsync(payload, callback || () => {})
+Provider.prototype.send = function (payload, callback) {
+  this.sendAsync(payload, callback || function () {})
 }
 
 Provider.prototype.isConnected = function () {