diff --git a/src/qt/qt_vmmanager_main.hpp b/src/qt/qt_vmmanager_main.hpp
index c3c541b4f..11381ec1a 100644
--- a/src/qt/qt_vmmanager_main.hpp
+++ b/src/qt/qt_vmmanager_main.hpp
@@ -68,7 +68,11 @@ public slots:
     void shutdownForceButtonPressed() const;
     void searchSystems(const QString &text) const;
     void newMachineWizard();
+#ifdef _WIN32
     void addNewSystem(const QString &name, const QString &dir, const QString &configFile = {});
+#else
+    void addNewSystem(const QString &name, const QString &dir, const QString &configFile);
+#endif
     [[nodiscard]] QStringList getSearchCompletionList() const;
     void modelDataChange();
     void onPreferencesUpdated();