diff --git a/src/kservice.c b/src/kservice.c
index 694cc735fa..da4d7980b6 100644
--- a/src/kservice.c
+++ b/src/kservice.c
@@ -279,7 +279,7 @@ void *rt_memmove(void *dest, const void *src, rt_ubase_t n)
 		s += n;
 
 		while (n--)
-			*tmp-- = *s--;
+			*(--tmp) = *(--s);
 	}
 	else
 	{