diff --git a/src/layouts/QskLayoutConstraint.h b/src/layouts/QskLayoutConstraint.h
index c2fcd553..26c4747a 100644
--- a/src/layouts/QskLayoutConstraint.h
+++ b/src/layouts/QskLayoutConstraint.h
@@ -11,6 +11,7 @@
 #include <qnamespace.h>
 #include <qsize.h>
 #include <limits>
+#include <functional>
 
 class QskSizePolicy;
 class QskControl;
@@ -19,8 +20,6 @@ class QQuickItem;
 class QSizeF;
 class QRectF;
 
-namespace std { template< typename T > class function; }
-
 namespace QskLayoutConstraint
 {
     enum Type