diff --git a/devtools/.eslintrc.js b/devtools/.eslintrc.js
index 75ad6c0e7319..b8d64487164b 100644
--- a/devtools/.eslintrc.js
+++ b/devtools/.eslintrc.js
@@ -13,15 +13,6 @@ module.exports = {
     "require": true,
   },
   "overrides": [{
-    // XXX Bug 1230193. We're still working on enabling no-undef for these test
-    // directories.
-    "files": [
-      "server/tests/mochitest/**",
-    ],
-    "rules": {
-      "no-undef": "off",
-    }
-  }, {
     "files": [
       "client/framework/**",
     ],
diff --git a/devtools/server/tests/mochitest/.eslintrc.js b/devtools/server/tests/mochitest/.eslintrc.js
index c5b919ce337f..c5009f62edd1 100644
--- a/devtools/server/tests/mochitest/.eslintrc.js
+++ b/devtools/server/tests/mochitest/.eslintrc.js
@@ -2,5 +2,5 @@
 
 module.exports = {
   // Extend from the common devtools mochitest eslintrc config.
-  "extends": "../../../.eslintrc.xpcshell.js"
+  "extends": "../../../.eslintrc.mochitests.js"
 };
diff --git a/devtools/server/tests/mochitest/Debugger.Source.prototype.element.js b/devtools/server/tests/mochitest/Debugger.Source.prototype.element.js
index 0fe4157a4401..095398ddadfd 100644
--- a/devtools/server/tests/mochitest/Debugger.Source.prototype.element.js
+++ b/devtools/server/tests/mochitest/Debugger.Source.prototype.element.js
@@ -1,4 +1,5 @@
 /* exported heinrichFun */
+/* global franz */
 "use strict";
 
 function heinrichFun() {
diff --git a/devtools/server/tests/mochitest/test_connectToFrame.html b/devtools/server/tests/mochitest/test_connectToFrame.html
index 6fa1159ae7da..33cde598acc7 100644
--- a/devtools/server/tests/mochitest/test_connectToFrame.html
+++ b/devtools/server/tests/mochitest/test_connectToFrame.html
@@ -14,6 +14,9 @@ Bug 966991 - Test DebuggerServer.connectToFrame
 <script type="application/javascript">
 "use strict";
 
+// Part of this is a frame script.
+/* eslint-env mozilla/frame-script */
+
 const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
 const { DebuggerClient } = require("devtools/shared/client/debugger-client");
 const { DebuggerServer } = require("devtools/server/main");
diff --git a/devtools/server/tests/mochitest/test_css-logic-media-queries.html b/devtools/server/tests/mochitest/test_css-logic-media-queries.html
index 237ab38bde91..72177f82dc90 100644
--- a/devtools/server/tests/mochitest/test_css-logic-media-queries.html
+++ b/devtools/server/tests/mochitest/test_css-logic-media-queries.html
@@ -31,6 +31,7 @@ Test that css-logic handles media-queries correctly
     const {require} = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
     const Services = require("Services");
     const {CssLogic} = require("devtools/server/actors/inspector/css-logic");
+    const InspectorUtils = require("InspectorUtils");
 
     SimpleTest.waitForExplicitFinish();
 
diff --git a/devtools/server/tests/mochitest/test_getProcess.html b/devtools/server/tests/mochitest/test_getProcess.html
index 7be06b5ba750..7744d8c36e3f 100644
--- a/devtools/server/tests/mochitest/test_getProcess.html
+++ b/devtools/server/tests/mochitest/test_getProcess.html
@@ -14,6 +14,9 @@ Bug 1060093 - Test DebuggerServer.getProcess
 <script type="application/javascript">
 "use strict";
 
+// Part of this is a frame script.
+/* eslint-env mozilla/frame-script */
+
 const {require} = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
 const {DebuggerClient} = require("devtools/shared/client/debugger-client");
 const {DebuggerServer} = require("devtools/server/main");
diff --git a/devtools/server/tests/mochitest/test_inspector-pseudoclass-lock.html b/devtools/server/tests/mochitest/test_inspector-pseudoclass-lock.html
index c70ba584269c..2703409152eb 100644
--- a/devtools/server/tests/mochitest/test_inspector-pseudoclass-lock.html
+++ b/devtools/server/tests/mochitest/test_inspector-pseudoclass-lock.html
@@ -20,6 +20,8 @@ window.onload = function() {
   runNextTest();
 };
 
+const InspectorUtils = require("InspectorUtils");
+
 let gInspectee = null;
 let gWalker = null;
 let gCleanupConnection = null;
diff --git a/devtools/server/tests/mochitest/test_webextension-addon-debugging-connect.html b/devtools/server/tests/mochitest/test_webextension-addon-debugging-connect.html
index 326dab624c29..49f63e7fe804 100644
--- a/devtools/server/tests/mochitest/test_webextension-addon-debugging-connect.html
+++ b/devtools/server/tests/mochitest/test_webextension-addon-debugging-connect.html
@@ -22,8 +22,10 @@ async function test_connect_addon(oopMode) {
   const extension = ExtensionTestUtils.loadExtension({
     useAddonManager: "temporary",
     background: function() {
+      /* eslint-disable no-undef */
       browser.test.log("background script executed");
       browser.test.sendMessage("background page ready");
+      /* eslint-enable no-undef */
     },
   });
   await extension.startup();