diff --git a/src/core/core.h b/src/core/core.h
index ec7b381e1..172e6da51 100644
--- a/src/core/core.h
+++ b/src/core/core.h
@@ -29,6 +29,8 @@
 #include <QMutex>
 #include <QObject>
 
+#include <functional>
+
 class CoreAV;
 class ICoreSettings;
 class GroupInvite;