diff --git a/src/routes/_utils/supportsFocusVisible.js b/src/routes/_utils/supportsFocusVisible.js
index c0914b1e..75f1df38 100644
--- a/src/routes/_utils/supportsFocusVisible.js
+++ b/src/routes/_utils/supportsFocusVisible.js
@@ -1,4 +1,7 @@
 import { thunk } from './thunk'
 import { supportsSelector } from './supportsSelector'
+import { isFirefox } from './userAgent/isFirefox'
 
-export const supportsFocusVisible = thunk(() => supportsSelector(':focus-visible'))
+// TODO: remove the Firefox check once this bug is fixed
+// https://bugzilla.mozilla.org/show_bug.cgi?id=1699154
+export const supportsFocusVisible = thunk(() => (!isFirefox() && supportsSelector(':focus-visible')))
diff --git a/src/routes/_utils/userAgent/isFirefox.js b/src/routes/_utils/userAgent/isFirefox.js
new file mode 100644
index 00000000..e431fc0b
--- /dev/null
+++ b/src/routes/_utils/userAgent/isFirefox.js
@@ -0,0 +1,3 @@
+export function isFirefox () {
+  return typeof InstallTrigger !== 'undefined' // https://stackoverflow.com/a/9851769/680742
+}