diff --git a/packages/backend/src/server/api/SigninApiService.ts b/packages/backend/src/server/api/SigninApiService.ts
index a56a2d85b..5f264bb73 100644
--- a/packages/backend/src/server/api/SigninApiService.ts
+++ b/packages/backend/src/server/api/SigninApiService.ts
@@ -97,10 +97,15 @@ export class SigninApiService {
 			reply.code(429);
 			return {
 				error: {
-					message: 'Too many failed attempts to sign in. Try again later.',
-					code: 'TOO_MANY_AUTHENTICATION_FAILURES',
+					message: 'Rate limit exceeded. Please try again later.',
+					code: 'RATE_LIMIT_EXCEEDED',
 					id: '22d05606-fbcf-421a-a2db-b32610dcfd1b',
-				},
+					info: {
+						message: 'Too many failed attempts to sign in.',
+						code: 'TOO_MANY_AUTHENTICATION_FAILURES',
+						id: '6c181469-ecb9-42d2-82c9-60db5486a819',
+					},
+				}
 			};
 		}
 
diff --git a/packages/frontend/src/os.ts b/packages/frontend/src/os.ts
index 9a5243926..5a1071a92 100644
--- a/packages/frontend/src/os.ts
+++ b/packages/frontend/src/os.ts
@@ -79,7 +79,7 @@ export async function apiErrorHandler(err: Misskey.api.APIError, endpoint?: stri
 	} else if (err.code === 'ROLE_PERMISSION_DENIED') {
 		title = i18n.ts.permissionDeniedError;
 		text = i18n.ts.permissionDeniedErrorDescription;
-	} else if (err.code?.startsWith('TOO_MANY')) {
+	} else if (err.code?.startsWith('TOO_MANY_')) {
 		title = i18n.ts.youCannotCreateAnymore;
 		text = `${i18n.ts.error}: ${err.id}`;
 	}