--- a/testing/marionette/components/marionette.js
+++ b/testing/marionette/components/marionette.js
@@ -263,17 +263,17 @@ const RECOMMENDED_PREFS = new Map([
   // Prevent starting into safe mode after application crashes
   ["toolkit.startup.max_resumed_crashes", -1],
 
 ]);
 
 const isRemote = Services.appinfo.processType ==
     Services.appinfo.PROCESS_TYPE_CONTENT;
 
-class MarionetteMainProcess {
+class MarionetteParentProcess {
   constructor() {
     this.server = null;
 
     // holds reference to ChromeWindow
     // used to run GFX sanity tests on Windows
     this.gfxWindow = null;
 
     // indicates that all pending window checks have been completed
@@ -303,17 +303,17 @@ class MarionetteMainProcess {
   }
 
   receiveMessage({name}) {
     switch (name) {
       case "Marionette:IsRunning":
         return this.running;
 
       default:
-        log.warn("Unknown IPC message to main process: " + name);
+        log.warn("Unknown IPC message to parent process: " + name);
         return null;
     }
   }
 
   observe(subject, topic) {
     log.debug(`Received observer notification ${topic}`);
 
     switch (topic) {
@@ -480,17 +480,17 @@ class MarionetteMainProcess {
     ]);
   }
 }
 
 class MarionetteContentProcess {
   get running() {
     let reply = Services.cpmm.sendSyncMessage("Marionette:IsRunning");
     if (reply.length == 0) {
-      log.warn("No reply from main process");
+      log.warn("No reply from parent process");
       return false;
     }
     return reply[0];
   }
 
   get QueryInterface() {
     return ChromeUtils.generateQI([Ci.nsIMarionette]);
   }
@@ -503,17 +503,17 @@ const MarionetteFactory = {
     if (outer) {
       throw Cr.NS_ERROR_NO_AGGREGATION;
     }
 
     if (!this.instance_) {
       if (isRemote) {
         this.instance_ = new MarionetteContentProcess();
       } else {
-        this.instance_ = new MarionetteMainProcess();
+        this.instance_ = new MarionetteParentProcess();
       }
     }
 
     return this.instance_.QueryInterface(iid);
   },
 };
 
 function Marionette() {}

--- a/testing/marionette/listener.js
+++ b/testing/marionette/listener.js
@@ -74,17 +74,17 @@ Object.defineProperty(this, "capabilitie
 });
 
 let legacyactions = new legacyaction.Chain();
 
 // last touch for each fingerId
 let multiLast = {};
 
 // TODO: Log.jsm is not e10s compatible (see https://bugzil.la/1411513),
-// query the main process for the current log level
+// query the parent process for the current log level
 const logger = Log.repository.getLogger("Marionette");
 if (logger.ownAppenders.length == 0) {
   let log = Services.cpmm.initialProcessData["Marionette:Log"];
   logger.level = log.level;
   logger.addAppender(new Log.DumpAppender());
 }
 
 // sandbox storage and name of the current sandbox