diff --git a/packages/frontend/src/components/MkPostForm.vue b/packages/frontend/src/components/MkPostForm.vue
index 2bf0992eb2..3d13cd439a 100644
--- a/packages/frontend/src/components/MkPostForm.vue
+++ b/packages/frontend/src/components/MkPostForm.vue
@@ -1271,6 +1271,7 @@ async function schedule() {
 		title: i18n.ts.schedulePost,
 	});
 	if (canceled) return;
+	if (result.getTime() <= Date.now()) return;
 
 	scheduledAt.value = result.getTime();
 }