diff --git a/src/include/timer.h b/src/include/timer.h
index 2a970c48..e94121c0 100644
--- a/src/include/timer.h
+++ b/src/include/timer.h
@@ -52,8 +52,7 @@
 #ifndef GUI_TIMER_H
     #define GUI_TIMER_H
 
-#define USEC_1S         1000000
-#define USEC_10MS       10000
+#include "constants.h"
 
 typedef struct _TIMER {
     HWND        hWnd;