diff --git a/gui/mainwindow.h b/gui/mainwindow.h
index dc8dfdd5e..7d9f6272f 100644
--- a/gui/mainwindow.h
+++ b/gui/mainwindow.h
@@ -36,7 +36,6 @@
 
 class ThreadHandler;
 class LogView;
-class HelpWindow;
 class Project;
 class ErrorItem;
 class StatsDialog;