diff --git a/rt-thread-version/rt-thread-standard/programming-manual/device/pulse_encoder/pulse_encoder.md b/rt-thread-version/rt-thread-standard/programming-manual/device/pulse_encoder/pulse_encoder.md
index 286f2a5c08a581047ae7500adeb5ab64eb8559aa..3604b7bb204f19754538c0ee1bcc2790f9a5101d 100644
--- a/rt-thread-version/rt-thread-standard/programming-manual/device/pulse_encoder/pulse_encoder.md
+++ b/rt-thread-version/rt-thread-standard/programming-manual/device/pulse_encoder/pulse_encoder.md
@@ -204,7 +204,7 @@ static int pulse_encoder_sample(int argc, char *argv[])
         return ret;
     }
 
-    for(rt_uint32 i; i <= 10; i++)
+    for(rt_uint32_t i=0; i <= 10; i++)
     {
         rt_thread_mdelay(500);
         /* 读取脉冲编码器计数值 */