diff --git a/include/DeviceModule.h b/include/DeviceModule.h
index eddad012e8384c13c28eb7833041f3d1618e4f85..4536831860fa37f28c3e08554f9280aa88fed5ab 100644
--- a/include/DeviceModule.h
+++ b/include/DeviceModule.h
@@ -268,7 +268,7 @@ namespace ChimeraTK {
 
     friend class Application;
     friend struct history::ServerHistory;
-    friend class detail::DeviceModuleProxy;
+    friend struct detail::DeviceModuleProxy;
 
     template<typename T>
     friend class ExceptionHandlingDecorator;