diff --git a/src/librssguard/gui/messagebox.h b/src/librssguard/gui/messagebox.h
index b12184f84..d2b6f1408 100644
--- a/src/librssguard/gui/messagebox.h
+++ b/src/librssguard/gui/messagebox.h
@@ -6,6 +6,8 @@
 #include <QDialogButtonBox>
 #include <QMessageBox>
 
+#include <functional>
+
 class MessageBox : public QMessageBox {
   Q_OBJECT