diff --git a/src/clock.c b/src/clock.c
index e5cf3ea75..86d15f146 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -24,7 +24,6 @@
 static rt_tick_t rt_tick;
 
 extern void rt_timer_check(void);
-extern void rt_timer_switch(void);
 
 /**
  * This function will init system tick and set it to zero.