diff --git a/src/plugins/coreplugin/icore.cpp b/src/plugins/coreplugin/icore.cpp
index 33b5beeee25..e62843b8a44 100644
--- a/src/plugins/coreplugin/icore.cpp
+++ b/src/plugins/coreplugin/icore.cpp
@@ -486,7 +486,7 @@ QWidget *ICore::currentContextWidget()
 }
 
 
-QWidget *ICore::mainWindow()
+QMainWindow *ICore::mainWindow()
 {
     return m_mainwindow;
 }
diff --git a/src/plugins/coreplugin/icore.h b/src/plugins/coreplugin/icore.h
index 6f7991466dc..b466a7f0db5 100644
--- a/src/plugins/coreplugin/icore.h
+++ b/src/plugins/coreplugin/icore.h
@@ -28,6 +28,7 @@
 #include "core_global.h"
 #include "id.h"
 
+#include <QMainWindow>
 #include <QObject>
 #include <QRect>
 #include <QSettings>
@@ -99,7 +100,7 @@ public:
     static QString versionString();
     static QString buildCompatibilityString();
 
-    static QWidget *mainWindow();
+    static QMainWindow *mainWindow();
     static QWidget *dialogParent();
     static QStatusBar *statusBar();
     /* Raises and activates the window for the widget. This contains workarounds for X11. */