diff -urEbwB swift-4.0/Swift/QtUI/UserSearch/QtUserSearchWindow.h swift-4.0.new/Swift/QtUI/UserSearch/QtUserSearchWindow.h
--- swift-4.0/Swift/QtUI/UserSearch/QtUserSearchWindow.h	2018-03-19 14:28:55.000000000 +0100
+++ swift-4.0.new/Swift/QtUI/UserSearch/QtUserSearchWindow.h	2018-06-12 12:01:32.980255186 +0200
@@ -9,6 +9,7 @@
 #include <set>
 
 #include <QWizard>
+#include <QAbstractItemModel>
 
 #include <Swiften/Base/Override.h>