diff --git a/src/plugins/qmldesigner/designercore/instances/positionernodeinstance.h b/src/plugins/qmldesigner/designercore/instances/positionernodeinstance.h
index 9369ad6832a9af92a1fc813525ba319d63565d1a..628b0d160749647244671a559c7056aeae9f453c 100644
--- a/src/plugins/qmldesigner/designercore/instances/positionernodeinstance.h
+++ b/src/plugins/qmldesigner/designercore/instances/positionernodeinstance.h
@@ -3,7 +3,9 @@
 
 #include "qmlgraphicsitemnodeinstance.h"
 
+QT_BEGIN_NAMESPACE
 class QDeclarativeBasePositioner;
+QT_END_NAMESPACE
 
 namespace QmlDesigner {
 namespace Internal {