diff --git a/gui/ecp5/mainwindow.h b/gui/ecp5/mainwindow.h
index f67f7a81..721c6c0b 100644
--- a/gui/ecp5/mainwindow.h
+++ b/gui/ecp5/mainwindow.h
@@ -43,7 +43,7 @@ class MainWindow : public BaseMainWindow
     void onProjectLoaded() override;
 
   protected Q_SLOTS:
-    virtual void new_proj();
+    void new_proj() override;
     void newContext(Context *ctx);
     void open_lpf();
     void open_base();
diff --git a/gui/generic/mainwindow.h b/gui/generic/mainwindow.h
index a4ce9958..bb6a4cf1 100644
--- a/gui/generic/mainwindow.h
+++ b/gui/generic/mainwindow.h
@@ -36,7 +36,7 @@ class MainWindow : public BaseMainWindow
     void createMenu();
 
   protected Q_SLOTS:
-    virtual void new_proj();
+    void new_proj() override;
     void newContext(Context *ctx);
 };
 
diff --git a/gui/ice40/mainwindow.h b/gui/ice40/mainwindow.h
index bb8ed75f..4a9a7d8e 100644
--- a/gui/ice40/mainwindow.h
+++ b/gui/ice40/mainwindow.h
@@ -44,7 +44,7 @@ class MainWindow : public BaseMainWindow
     void onProjectLoaded() override;
 
   protected Q_SLOTS:
-    virtual void new_proj();
+    void new_proj() override;
 
     void open_pcf();
     void save_asc();