diff -aur a/dix/ffs.c b/dix/ffs.c
--- a/dix/ffs.c	2006-07-05 11:31:36.000000000 -0700
+++ b/dix/ffs.c	2006-11-09 21:46:11.000000000 -0800
@@ -31,6 +31,7 @@
 ffs(int i)
 {
     int j;
+    if (i == 0) return 0;
     for (j = 1; (i & 1) == 0; j++)
 	i >>= 1;
     return j;