1 files changed, 4 insertions, 0 deletions
diff --git a/clock.h b/clock.h
index 35eaa5a..51a7a59 100644
--- a/clock.h
+++ b/clock.h
@@ -1,3 +1,5 @@
+#ifndef _CLOCK_H
+#define _CLOCK_H
 
 struct time {
   u8 second;
@@ -14,3 +16,5 @@ extern struct time time;
 void display_date(void);
 void display_time(void);
 void clock( void );
+
+#endif /* _CLOCK_H */