Index: README.md
===================================================================
--- a/README.md
+++ b/README.md
@@ -28,17 +28,17 @@
 ### Running the browser tests in a real browser
 
 The tests under `test/browser` require a browser environment. `npm test` will
 run these in a headless browser, with each module being loaded in a new frame.
 
 The default is to run in both Chromium (using the remote interface)
 and Firefox. You can select which runners to use by setting the
 BROWSER_TEST_RUNNERS environment, the default is
-"chromium_remote,firefox". Possible values (separated by a ',') are:
+"chromium_remote". Possible values (separated by a ',') are:
 
 - "chromium_remote": Chromium 60 (using the remote interface)
 - "chromium": Chrome 63 (using WebDriver)
 - "firefox": Firefox 56 (using WebDriver)
 
 You can not set a specific version of the browser at runtime.
 
 Linting
Index: test_runner.js
===================================================================
--- a/test_runner.js
+++ b/test_runner.js
@@ -42,17 +42,17 @@
 };
 
 function configureRunners()
 {
   let runners = "BROWSER_TEST_RUNNERS" in process.env ?
       process.env.BROWSER_TEST_RUNNERS.split(",") : [];
 
   if (runners.length == 0)
-    return ["chromium_remote", "firefox"];
+    return ["chromium_remote"];
 
   return runners.filter(runner => runnerDefinitions.hasOwnProperty(runner));
 }
 
 let runnerProcesses = configureRunners();
 
 function addTestPaths(testPaths, recurse)
 {