diff --git a/browser/components/extensions/test/browser/browser_ext_webRequest.js b/browser/components/extensions/test/browser/browser_ext_webRequest.js
index ab9f58480d9e..5bbe6cdd3988 100644
--- a/browser/components/extensions/test/browser/browser_ext_webRequest.js
+++ b/browser/components/extensions/test/browser/browser_ext_webRequest.js
@@ -26,6 +26,33 @@ function createHiddenBrowser(url) {
 
 let extension;
 let dummy = "http://mochi.test:8888/browser/browser/components/extensions/test/browser/file_dummy.html";
+let headers = {
+  request: {
+    add: {
+      "X-WebRequest-request": "text",
+      "X-WebRequest-request-binary": "binary",
+    },
+    modify: {
+      "user-agent": "WebRequest",
+    },
+    remove: [
+      "accept-encoding",
+    ],
+  },
+  response: {
+    add: {
+      "X-WebRequest-response": "text",
+      "X-WebRequest-response-binary": "binary",
+    },
+    modify: {
+      "server": "WebRequest",
+      "content-type": "text/html; charset=utf-8",
+    },
+    remove: [
+      "connection",
+    ],
+  },
+};
 
 add_task(function* setup() {
   // SelfSupport has a tendency to fire when running this test alone, without
@@ -41,6 +68,7 @@ add_task(function* test_newWindow() {
   let expect = {
     "file_dummy.html": {
       type: "main_frame",
+      headers,
     },
   };
   // NOTE: When running solo, favicon will be loaded at some point during
@@ -63,6 +91,7 @@ add_task(function* test_newTab() {
   let expect = {
     "file_dummy.html": {
       type: "main_frame",
+      headers,
     },
   };
   extension.sendMessage("set-expected", {expect, ignore: ["favicon.ico"]});
@@ -77,6 +106,7 @@ add_task(function* test_subframe() {
   let expect = {
     "file_dummy.html": {
       type: "main_frame",
+      headers,
     },
   };
   // test a content subframe attached to hidden window
diff --git a/toolkit/components/extensions/test/mochitest/head_webrequest.js b/toolkit/components/extensions/test/mochitest/head_webrequest.js
index 636776d0399a..8fb8b9584c82 100644
--- a/toolkit/components/extensions/test/mochitest/head_webrequest.js
+++ b/toolkit/components/extensions/test/mochitest/head_webrequest.js
@@ -90,6 +90,7 @@ function background(events) {
     expected.test[phase] = true;
 
     let headers = details[`${phase}Headers`];
+    browser.test.log(`headers are ${JSON.stringify(headers)}`);
     browser.test.assertTrue(Array.isArray(headers), `${phase}Headers array present`);
 
     let {add, modify, remove} = expected.headers[phase];