diff --git a/res/res_musiconhold.c b/res/res_musiconhold.c
index 13509fcbd9..84a44f3b75 100644
--- a/res/res_musiconhold.c
+++ b/res/res_musiconhold.c
@@ -695,7 +695,10 @@ static struct mohdata *mohalloc(struct mohclass *cl)
 	moh->f.offset = AST_FRIENDLY_OFFSET;
 
 	moh->parent = cl;
+
+	AST_RWLIST_WRLOCK(&mohclasses);
 	AST_LIST_INSERT_HEAD(&cl->members, moh, list);
+	AST_RWLIST_UNLOCK(&mohclasses);
 	
 	return moh;
 }