2 files changed, 2 insertions, 2 deletions

diff --git a/src/mailman/rest/docs/membership.txt b/src/mailman/rest/docs/membership.txt
index 70d4384ce..5867c0928 100644
--- a/src/mailman/rest/docs/membership.txt
+++ b/src/mailman/rest/docs/membership.txt
@@ -290,7 +290,7 @@ Anna tries to join a mailing list she's already a member of.
     ...           })
     Traceback (most recent call last):
     ...
-    HTTPError: HTTP Error 400: Bad Request
+    HTTPError: HTTP Error 409: Conflict
 
 Gwen tries to join the alpha mailing list using an invalid delivery mode.
 
diff --git a/src/mailman/rest/members.py b/src/mailman/rest/members.py
index a5a3dd02e..8c0593457 100644
--- a/src/mailman/rest/members.py
+++ b/src/mailman/rest/members.py
@@ -108,7 +108,7 @@ class AllMembers(_MemberBase):
                                   _optional=('real_name', 'delivery_mode'))
             member = service.join(**validator(request))
         except AlreadySubscribedError:
-            return http.bad_request([], b'Member already subscribed')
+            return http.conflict([], b'Member already subscribed')
         except NoSuchListError:
             return http.bad_request([], b'No such list')
         except InvalidEmailAddressError: