- Issue #3745: Fix hashlib to always reject unicode and non buffer-api
  supporting objects as input no matter how it was compiled (built in
  implementations or external openssl library).
(backported from a py3k branch)
diff --git a/Modules/md5.h b/Modules/md5.h
index 5eb6d6c..0ab0e68 100644
--- a/Modules/md5.h
+++ b/Modules/md5.h
@@ -79,7 +79,7 @@
 void md5_init(md5_state_t *pms);
 
 /* Append a string to the message. */
-void md5_append(md5_state_t *pms, const md5_byte_t *data, int nbytes);
+void md5_append(md5_state_t *pms, const md5_byte_t *data, unsigned int nbytes);
 
 /* Finish the message and return the digest. */
 void md5_finish(md5_state_t *pms, md5_byte_t digest[16]);