diff --git a/docs/i_u_m/i_u_m_install.en.md b/docs/i_u_m/i_u_m_install.en.md
index b25e6fa5d..ad9aa0b9d 100644
--- a/docs/i_u_m/i_u_m_install.en.md
+++ b/docs/i_u_m/i_u_m_install.en.md
@@ -76,7 +76,7 @@ nano mailcow.conf
 ```
 If you plan to use a reverse proxy, you can, for example, bind HTTPS to 127.0.0.1 on port 8443 and HTTP to 127.0.0.1 on port 8080.
 
-You may need to stop an existing pre-installed MTA which blocks port 25/tcp. See [this chapter](../post_installation/firststeps-local-mta.en.md) to learn how to reconfigure Postfix to run besides mailcow after a successful installation.
+You may need to stop an existing pre-installed MTA which blocks port 25/tcp. See [this chapter](../post_installation/firststeps-local_mta.en.md) to learn how to reconfigure Postfix to run besides mailcow after a successful installation.
 
 Some updates modify mailcow.conf and add new parameters. It is hard to keep track of them in the documentation. Please check their description and, if unsure, ask at the known channels for advise.