diff --git a/dnsapi/dns_internetbs.sh b/dnsapi/dns_internetbs.sh
index ba17083..05a1ada 100755
--- a/dnsapi/dns_internetbs.sh
+++ b/dnsapi/dns_internetbs.sh
@@ -137,7 +137,7 @@ _get_root() {
         return 0
       fi
 
-      p=i
+      p=${i}
       i=$(_math "$i" + 1)
     done
   fi