diff --git a/packages/services/auth-service/src/application/services/auth.service.ts b/packages/services/auth-service/src/application/services/auth.service.ts
index e096718..d164fcc 100644
--- a/packages/services/auth-service/src/application/services/auth.service.ts
+++ b/packages/services/auth-service/src/application/services/auth.service.ts
@@ -208,11 +208,15 @@ export class AuthService {
     phone?: string,
   ) {
     // Generate slug from company name (underscores for valid PostgreSQL schema names)
-    const slug = companyName
+    let slug = companyName
       .toLowerCase()
       .replace(/[^a-z0-9]+/g, '_')
       .replace(/(^_|_$)/g, '')
       .slice(0, 40);
+    // If company name is all non-ASCII (e.g. Chinese), slug will be empty — use UUID fallback
+    if (!slug) {
+      slug = crypto.randomUUID().replace(/-/g, '').slice(0, 16);
+    }
 
     // Check slug uniqueness
     const existingTenant = await this.tenantRepository.findOneBy({ slug });