diff --git a/matrix/synapse/README.md b/matrix/synapse/README.md
index a0835d6..5ba9220 100644
--- a/matrix/synapse/README.md
+++ b/matrix/synapse/README.md
@@ -112,6 +112,30 @@ After changing the database, restart Synapse and check whether it can connect
 and create the tables it needs.
 
 
+# Create admin
+
+Synapse doesn't create an admin account at install time, so you'll have to do
+that yourself.
+
+You need to set a `registration_shared_secret` for this, set that in
+`conf.d/keys.yaml` like this:
+
+```
+registration_shared_secret: xxxx
+```
+
+You can create such a key by running `pwgen -csn 52 1`. Restart Synapse after
+setting this key.
+
+Now create an admin user. Login and issue this command:
+
+```
+register_new_matrix_user -u admin -a -c /etc/matrix-synapse/conf.d/keys.yaml
+```
+
+This will ask for a password, choose a safe one.
+
+
 # Logging
 
 Logging is configured in `log.yaml`. Some logging should go to systemd, the