diff --git a/content/client-server-api/_index.md b/content/client-server-api/_index.md
index bf0bd704..892fd483 100644
--- a/content/client-server-api/_index.md
+++ b/content/client-server-api/_index.md
@@ -93,6 +93,8 @@ request being made was invalid.
 
 These error codes can be returned by any API endpoint:
 
+<!-- Please keep the error codes below in alphabetical order -->
+
 `M_BAD_JSON`
 : Request contained valid JSON, but it was malformed in some way, e.g.
 missing required keys, invalid values for keys.
@@ -181,12 +183,16 @@ code if the endpoint is implemented, but the incorrect HTTP method is used.
 : The account has been [suspended](#account-suspension) and can only be used for
 limited actions at this time.
 
+<!-- Please keep the error codes above in alphabetical order -->
+
 #### Other error codes
 
 The following error codes are specific to certain endpoints.
 
 <!-- TODO: move them to the endpoints that return them -->
 
+<!-- Please keep the error codes below in alphabetical order -->
+
 `M_BAD_STATE`
 : The state change requested cannot be performed, such as attempting to
 unban a user who is not banned.
@@ -270,6 +276,8 @@ for endpoints that prove authentication, such as [`/login`](#get_matrixclientv3l
 `M_USER_IN_USE`
 : Encountered when trying to register a user ID which has been taken.
 
+<!-- Please keep the error codes above in alphabetical order -->
+
 #### Rate limiting
 
 Homeservers SHOULD implement rate limiting to reduce the risk of being
diff --git a/content/identity-service-api.md b/content/identity-service-api.md
index 61d7bcb3..d899a469 100644
--- a/content/identity-service-api.md
+++ b/content/identity-service-api.md
@@ -70,6 +70,8 @@ the keys `error` and `errcode` MUST always be present.
 
 Some standard error codes are below:
 
+<!-- Please keep the error codes below in alphabetical order -->
+
 `M_EMAIL_SEND_ERROR`
 : There was an error sending an email. Typically seen when attempting to
 verify ownership of a given email address.
@@ -119,6 +121,8 @@ This is expected to be returned with a 404 HTTP status code if the endpoint is
 not implemented or a 405 HTTP status code if the endpoint is implemented, but
 the incorrect HTTP method is used.
 
+<!-- Please keep the error codes above in alphabetical order -->
+
 ## Privacy
 
 Identity is a privacy-sensitive issue. While the identity server exists