diff --git a/roles/phabricator/templates/local.json.j2 b/roles/phabricator/templates/local.json.j2
index f96c2cedd9..ba496b80b0 100644
--- a/roles/phabricator/templates/local.json.j2
+++ b/roles/phabricator/templates/local.json.j2
@@ -16,6 +16,7 @@
   "repository.default-local-path" : "{{ phabricator_repodir }}",
   "environment.append-paths" : ["/usr/libexec/git-core/"],
   "diffusion.ssh-user" : "{{ phabricator_vcs_user }}",
+  "diffusion.ssh-host" : "git.{{ external_hostname }}",
   "welcome.html" : "{{ lookup("file", "phabricator-welcome.html") }}",
   "ui.header-color" : "{{ phabricator_header_color }}",
   "metamta.default-address" : "phabricator@{{ phabricator_mail_domain }}",