--- src/xcb_auth.c.orig	2008-01-22 18:35:14.000000000 +0200
+++ src/xcb_auth.c	2008-01-22 18:37:03.000000000 +0200
@@ -247,7 +247,12 @@
 
     info->namelen = memdup(&info->name, authptr->name, authptr->name_length);
     if(info->namelen)
-	ret = compute_auth(info, authptr, sockname);
+    {
+        if (getsockname(fd, sockname, &socknamelen) == -1)
+            ret = 0;
+        else
+            ret = compute_auth(info, authptr, sockname);
+    }
     if(!ret)
     {
 	free(info->name);