diff --git a/offlineimap.conf b/offlineimap.conf
index 0a14689..bc72e11 100644
--- a/offlineimap.conf
+++ b/offlineimap.conf
@@ -778,6 +778,7 @@ remoteuser = username
 #
 # Mandatory parameters are "oauth2_client_id", "oauth2_client_secret" and
 # either "oauth2_refresh_token" or "oauth2_access_token".
+#
 # See below to learn how to get those.
 #
 # Specify the OAuth2 client id and secret to use for the connection..
@@ -809,9 +810,13 @@ remoteuser = username
 # allows offlineimap to obtain new access tokens.
 #
 # If you want to use a refresh token, make sure you disabled/removed any
-# oauth2_access_token option.
+# oauth2_access_token option. The access token is downloaded from the URL
+# defined in the oauth2_request_url configuration option.
+# If the type of the remote is IMAP, oauth2_request_url MUST be defined.
+# For Gmail, the default URL is https://accounts.google.com/o/oauth2/token.
 #
 #oauth2_access_token = ACCESS_TOKEN
+#oauth2_request_url = https://accounts.google.com/o/oauth2/token
 #oauth2_refresh_token = REFRESH_TOKEN
 
 ########## Passwords