--- udns-0.0.9.orig/rblcheck.c	2007-01-10 04:52:51.000000000 +0200
+++ udns-0.0.9/rblcheck.c	2007-09-01 17:00:58.021629838 +0300
@@ -98,6 +98,8 @@ static void *ecalloc(int size, int cnt) 
 }
 
 static void addzone(const char *zone) {
+  char *tmp;
+
   if (nzones >= nzalloc) {
     const char **zs = (const char**)ecalloc(sizeof(char*), (nzalloc += 16));
     if (zones) {
@@ -106,7 +108,9 @@ static void addzone(const char *zone) {
     }
     zones = zs;
   }
-  zones[nzones++] = zone;
+  tmp = strdup(zone);
+  if (!tmp) error(1, "out of memory");
+  zones[nzones++] = tmp;
 }
 
 static int addzonefile(const char *fname) {