--- a/devtools/client/commandline/test/browser_gcli_async.js
+++ b/devtools/client/commandline/test/browser_gcli_async.js
@@ -47,17 +47,17 @@ exports.testBasic = function (options) {
       check: {
         input:  "tsslow ",
         hints:         "Shalom",
         markup: "VVVVVVV",
         cursor: 7,
         current: "hello",
         status: "ERROR",
         predictions: [
-          "Shalom", "Namasté", "Hallo", "Dydd-da", "Chào", "Hej",
+          "Shalom", "Namast\u{00E9}", "Hallo", "Dydd-da", "Ch\u{00E0}o", "Hej",
           "Saluton", "Sawubona"
         ],
         unassigned: [ ],
         args: {
           command: { name: "tsslow" },
           hello: {
             arg: "",
             status: "INCOMPLETE"
@@ -69,17 +69,17 @@ exports.testBasic = function (options) {
       setup:    "tsslow S",
       check: {
         input:  "tsslow S",
         hints:          "halom",
         markup: "VVVVVVVI",
         cursor: 8,
         current: "hello",
         status: "ERROR",
-        predictions: [ "Shalom", "Saluton", "Sawubona", "Namasté" ],
+        predictions: [ "Shalom", "Saluton", "Sawubona", "Namast\u{00E9}" ],
         unassigned: [ ],
         args: {
           command: { name: "tsslow" },
           hello: {
             arg: " S",
             status: "INCOMPLETE"
           },
         }

--- a/devtools/client/commandline/test/head.js
+++ b/devtools/client/commandline/test/head.js
@@ -12,17 +12,17 @@ const TEST_BASE_HTTPS = "https://example
 
 var { require } = Cu.import("resource://devtools/shared/Loader.jsm", {});
 var { console } = require("resource://gre/modules/Console.jsm");
 var flags = require("devtools/shared/flags");
 
 // Import the GCLI test helper
 var testDir = gTestPath.substr(0, gTestPath.lastIndexOf("/"));
 Services.scriptloader.loadSubScript(testDir + "/helpers.js", this);
-Services.scriptloader.loadSubScript(testDir + "/mockCommands.js", this);
+Services.scriptloader.loadSubScript(testDir + "/mockCommands.js", this, "UTF-8");
 
 flags.testing = true;
 SimpleTest.registerCleanupFunction(() => {
   flags.testing = false;
 });
 
 function whenDelayedStartupFinished(aWindow, aCallback) {
   Services.obs.addObserver(function observer(aSubject, aTopic) {