diff --git a/README.md b/README.md
index ecad693..89b08ac 100755
--- a/README.md
+++ b/README.md
@@ -26,6 +26,10 @@ There is a slight delay between when a new tab is opened and the debugger starts
 
 While the chrome.debugger API is active, a bar under the address bar is displayed. Hiding the bar is only possible when the --silent-debugger-extension-api command-line switch is used.
 
+### FireFox
+
+Unfortunately it doesn't work on Firefox since Firefox doesn't support the debugger API for extensions. https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions#browser_compatibility
+
 ### Locale override does not mock language data
 
 Unlike the Chrome devtools location sensor, overriding the locale does not change language data (such as navigator.language or navigator.languages). There is an open ticket about this here: https://bugs.chromium.org/p/chromium/issues/detail?id=1306254