--- a/testing/marionette/listener.js
+++ b/testing/marionette/listener.js
@@ -663,17 +663,17 @@ function executeJSScript(msg) {
  * For executeAsync, it will return a response when marionetteScriptFinished/arguments[arguments.length-1]
  * method is called, or if it times out.
  */
 function executeWithCallback(msg, useFinish) {
   // Set up inactivity timeout.
   if (msg.json.inactivityTimeout) {
     let setTimer = function() {
       inactivityTimeoutId = curFrame.setTimeout(function() {
-        sandbox.asyncComplete(new ScriptTimeout("timed out due to inactivity"), asyncTestCommandId);
+        sandbox.asyncComplete(new ScriptTimeoutError("timed out due to inactivity"), asyncTestCommandId);
       }, msg.json.inactivityTimeout);
     };
 
     setTimer();
     heartbeatCallback = function() {
       curFrame.clearTimeout(inactivityTimeoutId);
       setTimer();
     };