diff --git a/alethzero/MainWin.h b/alethzero/MainWin.h
index ce1a9b670..7aee0c376 100644
--- a/alethzero/MainWin.h
+++ b/alethzero/MainWin.h
@@ -21,6 +21,9 @@
 
 #pragma once
 
+#ifdef Q_MOC_RUN
+#define BOOST_MPL_IF_HPP_INCLUDED
+#endif
 
 #include <map>
 #include <QtNetwork/QNetworkAccessManager>