diff --git a/byte/byte_copy.c b/byte/byte_copy.c
index e2f0737..f9ce794 100644
--- a/byte/byte_copy.c
+++ b/byte/byte_copy.c
@@ -5,7 +5,7 @@
 void byte_copy(void* out, unsigned int len, const void* in) {
   register char* s=out;
   register const char* t=in;
-  register const char* u=u+len;
+  register const char* u=t+len;
   if (len>127) {
     if (sizeof(unsigned long)>4) {	/* a good compiler should optimize this check away */
       for (;(unsigned long)t&7;) {