diff --git a/README.md b/README.md
index 62745b71..156e6a29 100644
--- a/README.md
+++ b/README.md
@@ -249,7 +249,7 @@ To generate coverage reports for the Javascript tests:
 - `PORT`: Integer specifying the port to bind to when running the flask server. Used only for local development.
 - `REDIS_URI`: URI for the redis server.
 - `SECRET_KEY`: String key which will be used to sign the session cookie. Should be a long string of random bytes. https://flask.palletsprojects.com/en/1.1.x/config/#SECRET_KEY
-- `SERVER_NAME`: Hostname for ATAT.
+- `SERVER_NAME`: Hostname for ATAT. Only needs to be specified in contexts where the hostname cannot be inferred from the request, such as Celery workers. https://flask.palletsprojects.com/en/1.1.x/config/#SERVER_NAME
 - `SESSION_COOKIE_NAME`: String value specifying the name to use for the session cookie. https://flask.palletsprojects.com/en/1.1.x/config/#SESSION_COOKIE_NAME
 - `SESSION_TYPE`: String value specifying the cookie storage backend. https://pythonhosted.org/Flask-Session/
 - `SESSION_USE_SIGNER`: Boolean value specifying if the cookie sid should be signed.