diff --git a/lib/Commands.cc b/lib/Commands.cc
index 3245b533..d9251a0a 100644
--- a/lib/Commands.cc
+++ b/lib/Commands.cc
@@ -313,6 +313,8 @@ SharedBuffer Commands::newAuthResponse(const AuthenticationPtr& authentication,
 
     if (authDataContent->hasDataFromCommand()) {
         authData->set_auth_data(authDataContent->getCommandData());
+    } else {
+        authData->set_auth_data("");
     }
 
     return writeMessageWithSize(cmd);