diff --git a/transport/include/hidl/LegacySupport.h b/transport/include/hidl/LegacySupport.h
index 2f0c3f3..f03d34d 100644
--- a/transport/include/hidl/LegacySupport.h
+++ b/transport/include/hidl/LegacySupport.h
@@ -74,7 +74,7 @@
     }
 
     joinRpcThreadpool();
-    return 0;
+    return UNKNOWN_ERROR;
 }
 template<class Interface>
 __attribute__((warn_unused_result))