diff --git a/src/Gui/DlgSettingsUnitsImp.cpp b/src/Gui/DlgSettingsUnitsImp.cpp
index 6ea6e9bde4..d7391b52c4 100644
--- a/src/Gui/DlgSettingsUnitsImp.cpp
+++ b/src/Gui/DlgSettingsUnitsImp.cpp
@@ -22,6 +22,7 @@
 
 #include "PreCompiled.h"
 #ifndef _PreComp_
+# include <cmath>
 # include <limits>
 # include <QApplication>
 #endif