--- src/xcb_auth.c.orig 2009-01-29 15:59:12.000000000 +0200
+++ src/xcb_auth.c      2009-01-29 15:57:14.045667000 +0200
@@ -251,7 +251,12 @@
 
     info->namelen = memdup(&info->name, authptr->name, authptr->name_length);
     if(info->namelen)
+    {
+       if (getsockname(fd, sockname, &socknamelen) == -1)
+            ret = 0;
+       else
        ret = compute_auth(info, authptr, sockname);
+    }
     if(!ret)
     {
        free(info->name);