diff --git a/packages/frontend/src/components/MkPostForm.vue b/packages/frontend/src/components/MkPostForm.vue
index f15906c1c..620b12682 100644
--- a/packages/frontend/src/components/MkPostForm.vue
+++ b/packages/frontend/src/components/MkPostForm.vue
@@ -228,7 +228,7 @@ const hashtags = $computed(defaultStore.makeGetterSetter('postFormHashtags'));
 
 watch($$(text), () => {
 	checkMissingMention();
-});
+}, { immediate: true });
 
 watch($$(visibleUsers), () => {
 	checkMissingMention();