diff --git a/packages/react-devtools-extensions/src/inject.js b/packages/react-devtools-extensions/src/inject.js
index 909a192b53e5..b2f4a03e1295 100644
--- a/packages/react-devtools-extensions/src/inject.js
+++ b/packages/react-devtools-extensions/src/inject.js
@@ -1,6 +1,6 @@
 /* global chrome */
 
-export default function inject(scriptName: string, done: ? Function) {
+export default function inject(scriptName: string, done: ?Function) {
   const source = `
   (function () {
     window.postMessage({ source: 'react-devtools-inject-script', scriptName: "${scriptName}" }, "*");
diff --git a/packages/react-devtools-extensions/src/injectGlobalHook.js b/packages/react-devtools-extensions/src/injectGlobalHook.js
index e35c675e1f29..dd8bf9def7b4 100644
--- a/packages/react-devtools-extensions/src/injectGlobalHook.js
+++ b/packages/react-devtools-extensions/src/injectGlobalHook.js
@@ -37,8 +37,8 @@ window.addEventListener('message', function(evt) {
         reactBuildType: evt.data.reactBuildType,
       };
       chrome.runtime.sendMessage(lastDetectionResult);
-    } else if (evt.data.source === 'react-devtools-inject-backend' && evt.data.scriptName) {
-      //Inject backend
+    } else if (evt.data.source === 'react-devtools-inject-script' && evt.data.scriptName) {
+      //Inject the specified script
       var script = document.constructor.prototype.createElement.call(document, 'script');
       script.src = evt.data.scriptName;
       script.charset = "utf-8";