diff --git a/src/frontends/qt4/GuiApplication.cpp b/src/frontends/qt4/GuiApplication.cpp
index 80bd6991ba..19e9b2bdfe 100644
--- a/src/frontends/qt4/GuiApplication.cpp
+++ b/src/frontends/qt4/GuiApplication.cpp
@@ -188,6 +188,7 @@ void setLocale()
 	}
 	Messages::guiLanguage(fromqstr(theLocale.name()));
 	QLocale::setDefault(theLocale);
+	setlocale(LC_NUMERIC, "C");
 }