diff --git a/include/rtthread.h b/include/rtthread.h
index ea7806599f7d6d9a9abdc76f70cd6a048e387024..c3bc0516b529780f7c720089b9f95c671be35d33 100644
--- a/include/rtthread.h
+++ b/include/rtthread.h
@@ -63,6 +63,7 @@ void rt_object_put_sethook(void (*hook)(struct rt_object* object));
  */
 void rt_system_tick_init(void);
 rt_tick_t rt_tick_get(void);
+void rt_tick_set(rt_tick_t tick);
 void rt_tick_increase(void);
 rt_tick_t rt_tick_from_millisecond(rt_uint32_t ms);
 
diff --git a/src/clock.c b/src/clock.c
index 9203fc57ede1a8bd77c0fe390c8e3ab32718ba12..f23ddc327992c1a5e106e163b014cb0d3b7cf512 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -15,8 +15,10 @@
  * 2010-03-08     Bernard      remove rt_passed_second
  * 2010-05-20     Bernard      fix the tick exceeds the maximum limits
  * 2010-07-13     Bernard      fix rt_tick_from_millisecond issue found by kuronca
+ * 2011-06-26     Bernard      add rt_tick_set function.
  */
 
+#include <rthw.h>
 #include <rtthread.h>
 
 static rt_tick_t rt_tick;
@@ -51,6 +53,19 @@ rt_tick_t rt_tick_get()
 	return rt_tick;
 }
 
+/**
+ * This function will set current tick
+ */
+void rt_tick_set(rt_tick_t tick)
+{
+	rt_base_t level;
+	level = rt_hw_interrupt_disable();
+
+	rt_tick = tick;
+	
+	rt_hw_interrupt_enable(level);
+}
+
 /**
  * This function will notify kernel there is one tick passed. Normally,
  * this function is invoked by clock ISR.
diff --git a/src/kservice.c b/src/kservice.c
index 295a9178428140cffa2b181b281a94e4ac57e464..10d280708206d2ff06763003382946e8cf2fe2c4 100644
--- a/src/kservice.c
+++ b/src/kservice.c
@@ -44,7 +44,11 @@ rt_err_t rt_get_errno(void)
 {
 	rt_thread_t tid;
 
-	RT_DEBUG_NOT_IN_INTERRUPT;
+	if(rt_interrupt_get_nest() != 0)
+	{
+		/* it's in interrupt context */
+		return errno;
+	}
 
 	tid = rt_thread_self();
 	if (tid == RT_NULL) return errno;
@@ -61,7 +65,12 @@ void rt_set_errno(rt_err_t error)
 {
 	rt_thread_t tid;
 
-	RT_DEBUG_NOT_IN_INTERRUPT;
+	if(rt_interrupt_get_nest() != 0)
+	{
+		/* it's in interrupt context */
+		errno = error;
+		return;
+	}
 
 	tid = rt_thread_self();
 	if (tid == RT_NULL) { errno = error; return; }