diff --git a/tools/mtrack-test.c b/tools/mtrack-test.c
index 2f455a4..88ed60b 100644
--- a/tools/mtrack-test.c
+++ b/tools/mtrack-test.c
@@ -23,6 +23,7 @@
 #include "mtouch.h"
 #include <fcntl.h>
 #include <stdarg.h>
+#include <unistd.h>
 
 void xf86Msg(int type, const char *format, ...)
 {