diff --git a/kcmkwin/kwinoptions/mouse.cpp b/kcmkwin/kwinoptions/mouse.cpp
index b64b7e9f35..e1ecf0632f 100644
--- a/kcmkwin/kwinoptions/mouse.cpp
+++ b/kcmkwin/kwinoptions/mouse.cpp
@@ -37,6 +37,8 @@
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 
+#include <stdlib.h>
+
 #include "mouse.h"
 #include "mouse.moc"