diff --git a/src/application/services/auth.rs b/src/application/services/auth.rs
index d956c29..5447f21 100644
--- a/src/application/services/auth.rs
+++ b/src/application/services/auth.rs
@@ -132,7 +132,15 @@ impl AuthService {
         .bind(&req.email)
         .bind(&hashed)
         .fetch_one(&mut *tx)
-        .await?;
+        .await
+        .map_err(|e| {
+            if let sqlx::Error::Database(db) = &e
+                && db.is_unique_violation()
+            {
+                return AppError::AlreadyExists("User already exists".into());
+            }
+            e.into()
+        })?;
 
         let user_count: i64 = sqlx::query_scalar("SELECT COUNT(1) FROM users WHERE tenant_id = $1")
             .bind(tenant_id)
@@ -412,4 +420,3 @@ impl AuthService {
         })
     }
 }
-