diff --git a/doc/install/installation.md b/doc/install/installation.md
index 459a21ae8214c10f6d492a2c318879277188e70e..feeda612a5e8c078211eef5edbc5a464f57aca88 100644
--- a/doc/install/installation.md
+++ b/doc/install/installation.md
@@ -286,6 +286,8 @@ GitLab Shell is an SSH access and repository management software developed speci
 
 **Note:** If you want to use HTTPS, see [Using HTTPS](#using-https) for the additional steps.
 
+**Note:** Make sure your hostname can be resolved on the machine itself by either a proper DNS record or an additional line in /etc/hosts ("127.0.0.1  hostname"). This might be necessary for example if you set up gitlab behind a reverse proxy. If the hostname cannot be resolved, the final installation check will fail with "Check GitLab API access: FAILED. code: 401" and pushing commits will be rejected with "[remote rejected] master -> master (hook declined)".
+
 ### Initialize Database and Activate Advanced Features
 
     sudo -u git -H bundle exec rake gitlab:setup RAILS_ENV=production