diff --git a/include/ascs/ext/unpacker.h b/include/ascs/ext/unpacker.h
index b1b4cc3269c728b145b7ef926288d365a10cf2c0..e745e60015548fc848bedd4bbb1caf1942545e36 100644
--- a/include/ascs/ext/unpacker.h
+++ b/include/ascs/ext/unpacker.h
@@ -81,7 +81,7 @@ public:
 		if (unpack_ok && remain_len > 0)
 		{
 			auto pnext = std::next(msg_pos_can.back().first, msg_pos_can.back().second);
-			memcpy(&*std::begin(raw_buff), pnext, remain_len); //left behind unparsed data
+			memmove(&*std::begin(raw_buff), pnext, remain_len); //left behind unparsed data
 		}
 
 		//if unpacking failed, successfully parsed msgs will still returned via msg_can(sticky package), please note.
@@ -405,7 +405,7 @@ public:
 		if (pnext == &*std::begin(raw_buff)) //we should have at least got one msg.
 			return false;
 		else if (remain_len > 0)
-			memcpy(&*std::begin(raw_buff), pnext, remain_len); //left behind unparsed msg
+			memmove(&*std::begin(raw_buff), pnext, remain_len); //left behind unparsed msg
 
 		return true;
 	}