diff --git a/packages/frontend/src/components/MkSignupDialog.form.vue b/packages/frontend/src/components/MkSignupDialog.form.vue
index 3d1c44fc90..e1f4e26d62 100644
--- a/packages/frontend/src/components/MkSignupDialog.form.vue
+++ b/packages/frontend/src/components/MkSignupDialog.form.vue
@@ -277,7 +277,7 @@ async function onSubmit(): Promise<void> {
 		return null;
 	});
 
-	if (res) {
+	if (res && res.ok) {
 		if (res.status === 204 || instance.emailRequiredForSignup) {
 			os.alert({
 				type: 'success',
@@ -295,6 +295,8 @@ async function onSubmit(): Promise<void> {
 				await login(resJson.token);
 			}
 		}
+	} else {
+		onSignupApiError();
 	}
 
 	submitting.value = false;