diff --git a/src/client/app/common/views/components/signin.vue b/src/client/app/common/views/components/signin.vue
index 5230ac371..aad9a1b7c 100644
--- a/src/client/app/common/views/components/signin.vue
+++ b/src/client/app/common/views/components/signin.vue
@@ -53,8 +53,9 @@ export default Vue.extend({
 			this.signing = true;
 
 			(this as any).api('signin', {
-				username: this.username,
-				password: this.password,
+				// password という名前(または username とのペア？)では何らかのフィルタリングがされるっぽい？
+				x: this.username,
+				y: this.password,
 				token: this.user && this.user.twoFactorEnabled ? this.token : undefined
 			}).then(() => {
 				location.reload();
diff --git a/src/server/api/private/signin.ts b/src/server/api/private/signin.ts
index 65413208d..32d3eecae 100644
--- a/src/server/api/private/signin.ts
+++ b/src/server/api/private/signin.ts
@@ -12,8 +12,8 @@ export default async (ctx: Koa.Context) => {
 	ctx.set('Access-Control-Allow-Credentials', 'true');
 
 	const body = ctx.request.body as any;
-	const username = body['username'];
-	const password = body['password'];
+	const username = body['username'] || body['x'];
+	const password = body['password'] || body['y'];
 	const token = body['token'];
 
 	if (typeof username != 'string') {