diff --git a/src/plugins/qmlprojectmanager/qmlmainfileaspect.h b/src/plugins/qmlprojectmanager/qmlmainfileaspect.h
index 2c1b047ea37..286d000d3d3 100644
--- a/src/plugins/qmlprojectmanager/qmlmainfileaspect.h
+++ b/src/plugins/qmlprojectmanager/qmlmainfileaspect.h
@@ -34,7 +34,10 @@
 namespace Core {
 class IEditor;
 }
+
+QT_BEGIN_NAMESPACE
 class QComboBox;
+QT_END_NAMESPACE
 
 namespace QmlProjectManager {