diff --git a/jskeycodes.py b/jskeycodes.py
index 0cdcca3..a359a0e 100644
--- a/jskeycodes.py
+++ b/jskeycodes.py
@@ -122,6 +122,10 @@ jskeycodes = {
     'KEY_MOD_LMETA': 'MetaLeft',
     'KEY_MOD_RMETA': 'MetaRight',
 
+# Because firefox must sending different
+    'KEY_MOD_LMETA': 'OSLeft',
+    'KEY_MOD_RMETA': 'OSRight',
+
     'KEY_COMPOSE': 'ContextMenu',
 }