diff --git a/README.md b/README.md
index ce57ff2..9410734 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,7 @@ The auth script is invoked by [Certbot](https://certbot.eff.org/)'s `--manual-au
 ### Requirements
 * Certbot
 * PHP & Composer
+* dig - DNS lookup utility
 * A TransIP account (and the domain registered you want a certificate for ;-)
 * API access enabled for this account (https://www.transip.eu/knowledgebase/entry/77-want-use-the-transip-api/)
 * The private key generated in above process
@@ -23,3 +24,8 @@ Ok, the boring part is over.. let's get a shiny Letsencrypt certificate :)
 Example:
 
 `# certbot certonly --manual --preferred-challenges=dns --manual-auth-hook transip-dns-auth --manual-cleanup-hook transip-dns-cleanup -d example.com -d www.example.com`
+
+## Limitations
+Currently tested with a limited number of domains. Please be careful as this script overwrites your DNS zone (keeping all the current records, of course).
+
+You can always do a test run by commenting out `$transipDns->commit()` and printing the `$dnsEntries` array in the `transip-dns-auth` and `transip-dns-cleanup` scripts to make sure nothing weird happens to your zone.