diff -ru gdnsd-1.11.3.orig/gdnsd/zscan_djb.c gdnsd-1.11.3/gdnsd/zscan_djb.c
--- gdnsd-1.11.3.orig/gdnsd/zscan_djb.c	2014-08-01 08:22:55.000000000 -0300
+++ gdnsd-1.11.3/gdnsd/zscan_djb.c	2014-08-01 08:49:37.338082860 -0300
@@ -226,6 +226,9 @@
     unsigned int i;
     unsigned int j;
 
+    if (f->len < 2)
+      return;
+
     j = 0;
     i = 0;
     while (i < f->len) {