diff --git a/scripts/spellcheck/dicts/emqx.txt b/scripts/spellcheck/dicts/emqx.txt
index ea1c76d96..533269c87 100644
--- a/scripts/spellcheck/dicts/emqx.txt
+++ b/scripts/spellcheck/dicts/emqx.txt
@@ -170,6 +170,7 @@ libcoap
 lifecycle
 localhost
 lwm
+mcast
 mnesia
 mountpoint
 mqueue