diff --git a/README.md b/README.md
index b4cbf77..f575ae4 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,7 @@ Because any other "Whats my IP?"-tool sucks.
 
 Try it here: https://ip.clerie.de
 
+## About this software
 It's just one nginx site config. Feel free to host it yourself. It's open-source.
 
 ip.clerie.de is the HTML page with some JavaScript. This page needs an A and AAAA record in DNS.
@@ -10,3 +11,11 @@ ip.clerie.de is the HTML page with some JavaScript. This page needs an A and AAA
 ip4.clerie.de and ip6.clerie.de just returns the remote addr.
 
 ip4.clerie.de has only an A record. ip6.clerie.de has only an AAAA record.
+
+If you want host this yourself you have to replace all hardcoded domains. You can use the following sed command. Don't forget to change `IP.EXAMPLE.COM`, `IP4.EXAMPLE.COM` and `IP6.EXAMPLE.COM` to your own.
+
+```
+sed -e '/git.clerie.de/!s/ip.clerie.de/IP.EXAMPLE.COM/g;s/ip4.clerie.de/IP4.EXAMPLE.COM/g;s/ip6.clerie.de/IP6.EXAMPLE.COM/g' ip.clerie.de
+```
+
+The first match is to exclude the line with the link to the git repo from replacing.