diff --git a/include/transport/userregistry.h b/include/transport/userregistry.h
index 63d14a1ece047328520c2843cb16b2ed00e1470c..5b92298586d0bbd86ebb994469d51030208a41ac 100644
--- a/include/transport/userregistry.h
+++ b/include/transport/userregistry.h
@@ -102,6 +102,7 @@ class UserRegistry : public Swift::UserRegistry {
 
 		mutable std::map<std::string, Sess> users;
 		mutable Config *config;
+		std::string empty;
 };
 
 }