diff --git a/kernel/string.c b/kernel/string.c
index d99e612..153536f 100644
--- a/kernel/string.c
+++ b/kernel/string.c
@@ -33,6 +33,9 @@ memmove(void *dst, const void *src, uint n)
   const char *s;
   char *d;
 
+  if(n == 0)
+    return dst;
+  
   s = src;
   d = dst;
   if(s < d && s + n > d){