diff --git a/ui/widgets/checkbox.cpp b/ui/widgets/checkbox.cpp
index 7cc28a8..450810a 100644
--- a/ui/widgets/checkbox.cpp
+++ b/ui/widgets/checkbox.cpp
@@ -12,6 +12,7 @@
 #include "ui/painter.h"
 
 #include <QtGui/QtEvents>
+#include <QtCore/QtMath>
 
 namespace Ui {
 namespace {