--- a/master/mailbox.c	Thu Aug 13 15:18:53 2009 +0200
+++ b/master/mailbox.c	Mon Oct 19 13:12:40 2009 +0200
@@ -66,7 +66,7 @@
     total_size = EC_MBOX_HEADER_SIZE + size;
 
     if (unlikely(total_size > slave->configured_rx_mailbox_size)) {
-        EC_ERR("Data size (%u) does not fit in mailbox (%u)!\n",
+        EC_ERR("Data size (%zu) does not fit in mailbox (%u)!\n",
                 total_size, slave->configured_rx_mailbox_size);
         return ERR_PTR(-EOVERFLOW);
     }