diff --git a/kernel/kernel.c b/kernel/kernel.c
index d46ab98..b2159e8 100644
--- a/kernel/kernel.c
+++ b/kernel/kernel.c
@@ -146,7 +146,8 @@ inline void preempt_count_inc(void)
 
 inline void preempt_count_dec(void)
 {
-    preempt_cnt--;
+    if (preempt_cnt > 0)
+        preempt_cnt--;
 }
 
 void preempt_disable(void)