diff --git a/libs/wire-api-federation/src/Wire/API/Federation/API/Common.hs b/libs/wire-api-federation/src/Wire/API/Federation/API/Common.hs
index 265a40f7fd0..81fa5e70f55 100644
--- a/libs/wire-api-federation/src/Wire/API/Federation/API/Common.hs
+++ b/libs/wire-api-federation/src/Wire/API/Federation/API/Common.hs
@@ -23,7 +23,8 @@ import Test.QuickCheck
 import Wire.Arbitrary
 
 -- | This is equivalent to '()', but JSONifies to an empty object instead of an
--- empty array.
+-- empty array. Returning an empty object gives us more flexibility, allowing
+-- us to expand the response without breaking compatibility.
 data EmptyResponse = EmptyResponse
   deriving stock (Eq, Show, Generic)
   deriving (Arbitrary) via (GenericUniform EmptyResponse)
diff --git a/libs/wire-api-federation/src/Wire/API/Federation/API/Galley.hs b/libs/wire-api-federation/src/Wire/API/Federation/API/Galley.hs
index 2d655ec4804..39e594f08ff 100644
--- a/libs/wire-api-federation/src/Wire/API/Federation/API/Galley.hs
+++ b/libs/wire-api-federation/src/Wire/API/Federation/API/Galley.hs
@@ -54,14 +54,14 @@ type GalleyApi =
   -- that are part of a conversation at creation time. Since MLS conversations
   -- are always created empty (i.e. they only contain the creator), this RPC is
   -- never invoked for such conversations.
-  FedEndpoint "on-conversation-created" (ConversationCreated ConvId) ()
+  FedEndpoint "on-conversation-created" (ConversationCreated ConvId) EmptyResponse
     -- This endpoint is called the first time a user from this backend is
     -- added to a remote conversation.
     :<|> FedEndpoint "on-new-remote-conversation" NewRemoteConversation EmptyResponse
     :<|> FedEndpoint "get-conversations" GetConversationsRequest GetConversationsResponse
     -- used by the backend that owns a conversation to inform this backend of
     -- changes to the conversation
-    :<|> FedEndpoint "on-conversation-updated" ConversationUpdate ()
+    :<|> FedEndpoint "on-conversation-updated" ConversationUpdate EmptyResponse
     :<|> FedEndpointWithMods
            '[ MakesFederatedCall 'Galley "on-conversation-updated",
               MakesFederatedCall 'Galley "on-mls-message-sent",
diff --git a/services/galley/src/Galley/API/Federation.hs b/services/galley/src/Galley/API/Federation.hs
index 6d000766fa2..81ce504c6e2 100644
--- a/services/galley/src/Galley/API/Federation.hs
+++ b/services/galley/src/Galley/API/Federation.hs
@@ -155,7 +155,7 @@ onConversationCreated ::
   ) =>
   Domain ->
   F.ConversationCreated ConvId ->
-  Sem r ()
+  Sem r EmptyResponse
 onConversationCreated domain rc = do
   let qrc = fmap (toRemoteUnsafe domain) rc
   loc <- qualifyLocal ()
@@ -188,6 +188,7 @@ onConversationCreated domain rc = do
             (F.ccTime qrcConnected)
             (EdConversation c)
     pushConversationEvent Nothing event (qualifyAs loc [qUnqualified . Public.memId $ mem]) []
+  pure EmptyResponse
 
 onNewRemoteConversation ::
   Member ConversationStore r =>
@@ -226,10 +227,11 @@ onConversationUpdated ::
   ) =>
   Domain ->
   F.ConversationUpdate ->
-  Sem r ()
-onConversationUpdated requestingDomain cu =
+  Sem r EmptyResponse
+onConversationUpdated requestingDomain cu = do
   let rcu = toRemoteUnsafe requestingDomain cu
-   in void $ updateLocalStateOfRemoteConv rcu Nothing
+  void $ updateLocalStateOfRemoteConv rcu Nothing
+  pure EmptyResponse
 
 -- as of now this will not generate the necessary events on the leaver's domain
 leaveConversation ::
diff --git a/services/galley/test/integration/API.hs b/services/galley/test/integration/API.hs
index c5f857ae9fe..7cb47d63886 100644
--- a/services/galley/test/integration/API.hs
+++ b/services/galley/test/integration/API.hs
@@ -2159,7 +2159,7 @@ paginateConvListIds = do
               F.cuAlreadyPresentUsers = [],
               F.cuAction = SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (pure qAlice) roleNameWireMember)
             }
-    runFedClient @"on-conversation-updated" fedGalleyClient chadDomain cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient chadDomain cu
 
   remoteDee <- randomId
   let deeDomain = Domain "dee.example.com"
@@ -2175,7 +2175,7 @@ paginateConvListIds = do
               F.cuAlreadyPresentUsers = [],
               F.cuAction = SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (pure qAlice) roleNameWireMember)
             }
-    runFedClient @"on-conversation-updated" fedGalleyClient deeDomain cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient deeDomain cu
 
   -- 1 Proteus self conv + 1 MLS self conv + 2 convs with bob and eve + 196
   -- local convs + 25 convs on chad.example.com + 31 on dee.example = 256 convs.
@@ -2220,7 +2220,7 @@ paginateConvListIdsPageEndingAtLocalsAndDomain = do
               F.cuAlreadyPresentUsers = [],
               F.cuAction = SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (pure qAlice) roleNameWireMember)
             }
-    runFedClient @"on-conversation-updated" fedGalleyClient chadDomain cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient chadDomain cu
 
   remoteDee <- randomId
   let deeDomain = Domain "dee.example.com"
@@ -2238,7 +2238,7 @@ paginateConvListIdsPageEndingAtLocalsAndDomain = do
               F.cuAlreadyPresentUsers = [],
               F.cuAction = SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (pure qAlice) roleNameWireMember)
             }
-    runFedClient @"on-conversation-updated" fedGalleyClient deeDomain cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient deeDomain cu
 
   foldM_ (getChunkedConvs 16 0 alice) Nothing [4, 3, 2, 1, 0 :: Int]
 
@@ -3897,7 +3897,7 @@ putRemoteConvMemberOk update = do
             cuAction =
               SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (pure qalice) roleNameWireMember)
           }
-  runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cu
+  void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cu
 
   -- Expected member state
   let memberAlice =
@@ -4042,7 +4042,7 @@ putRemoteReceiptModeOk = do
             cuAction =
               SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (pure qalice) roleNameWireAdmin)
           }
-  runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cuAddAlice
+  void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cuAddAlice
 
   -- add another user adam as member
   qadam <- randomQualifiedUser
@@ -4057,7 +4057,7 @@ putRemoteReceiptModeOk = do
             cuAction =
               SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (pure qadam) roleNameWireMember)
           }
-  runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cuAddAdam
+  void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cuAddAdam
 
   let newReceiptMode = ReceiptMode 42
   let action = ConversationReceiptModeUpdate newReceiptMode
@@ -4373,10 +4373,10 @@ removeUser = do
             F.ccReceiptMode = Nothing,
             F.ccProtocol = ProtocolProteus
           }
-  runFedClient @"on-conversation-created" fedGalleyClient bDomain $ nc convB1 bart [alice, alexDel]
-  runFedClient @"on-conversation-created" fedGalleyClient bDomain $ nc convB2 bart [alexDel]
-  runFedClient @"on-conversation-created" fedGalleyClient cDomain $ nc convC1 carl [alexDel]
-  runFedClient @"on-conversation-created" fedGalleyClient dDomain $ nc convD1 dory [alexDel]
+  void $ runFedClient @"on-conversation-created" fedGalleyClient bDomain $ nc convB1 bart [alice, alexDel]
+  void $ runFedClient @"on-conversation-created" fedGalleyClient bDomain $ nc convB2 bart [alexDel]
+  void $ runFedClient @"on-conversation-created" fedGalleyClient cDomain $ nc convC1 carl [alexDel]
+  void $ runFedClient @"on-conversation-created" fedGalleyClient dDomain $ nc convD1 dory [alexDel]
 
   WS.bracketR3 c alice' alexDel' amy' $ \(wsAlice, wsAlexDel, wsAmy) -> do
     let handler = do
diff --git a/services/galley/test/integration/API/Federation.hs b/services/galley/test/integration/API/Federation.hs
index 06874ca642c..64f133de24a 100644
--- a/services/galley/test/integration/API/Federation.hs
+++ b/services/galley/test/integration/API/Federation.hs
@@ -247,7 +247,7 @@ addLocalUser = do
               SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (qalice :| [qdee]) roleNameWireMember)
           }
   WS.bracketRN c [alice, charlie, dee] $ \[wsA, wsC, wsD] -> do
-    runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cu
     liftIO $ do
       WS.assertMatch_ (5 # Second) wsA $
         wsAssertMemberJoinWithRole qconv qbob [qalice] roleNameWireMember
@@ -301,7 +301,7 @@ addUnconnectedUsersOnly = do
                 SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (qCharlie :| []) roleNameWireMember)
             }
     -- Alice receives no notifications from this
-    runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cu
     WS.assertNoEvent (5 # Second) [wsA]
 
 -- | This test invokes the federation endpoint:
@@ -346,9 +346,9 @@ removeLocalUser = do
 
   connectWithRemoteUser alice qBob
   WS.bracketR c alice $ \ws -> do
-    runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cuAdd
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cuAdd
     afterAddition <- listRemoteConvs remoteDomain alice
-    runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cuRemove
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain cuRemove
     liftIO $ do
       void . WS.assertMatch (3 # Second) ws $
         wsAssertMemberJoinWithRole qconv qBob [qAlice] roleNameWireMember
@@ -409,21 +409,21 @@ removeRemoteUser = do
           }
 
   WS.bracketRN c [alice, charlie, dee, flo] $ \[wsA, wsC, wsD, wsF] -> do
-    runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain (cuRemove qEve)
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain (cuRemove qEve)
     liftIO $ do
       WS.assertMatchN_ (3 # Second) [wsA, wsD] $
         wsAssertMembersLeave qconv qBob [qEve]
       WS.assertNoEvent (1 # Second) [wsC, wsF]
 
   WS.bracketRN c [alice, charlie, dee, flo] $ \[wsA, wsC, wsD, wsF] -> do
-    runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain (cuRemove qDee)
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain (cuRemove qDee)
     liftIO $ do
       WS.assertMatchN_ (3 # Second) [wsA, wsD] $
         wsAssertMembersLeave qconv qBob [qDee]
       WS.assertNoEvent (1 # Second) [wsC, wsF]
 
   WS.bracketRN c [alice, charlie, dee, flo] $ \[wsA, wsC, wsD, wsF] -> do
-    runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain (cuRemove qFlo)
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient remoteDomain (cuRemove qFlo)
     liftIO $ do
       WS.assertMatchN_ (3 # Second) [wsA] $
         wsAssertMembersLeave qconv qBob [qFlo]
@@ -460,7 +460,7 @@ notifyUpdate extras action etype edata = do
             FedGalley.cuAction = action
           }
   WS.bracketR2 c alice charlie $ \(wsA, wsC) -> do
-    runFedClient @"on-conversation-updated" fedGalleyClient bdom cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient bdom cu
     liftIO $ do
       WS.assertMatch_ (5 # Second) wsA $ \n -> do
         let e = List1.head (WS.unpackPayload n)
@@ -637,7 +637,7 @@ notifyDeletedConversation = do
               FedGalley.cuAlreadyPresentUsers = [alice],
               FedGalley.cuAction = SomeConversationAction (sing @'ConversationDeleteTag) ()
             }
-    runFedClient @"on-conversation-updated" fedGalleyClient bobDomain cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient bobDomain cu
 
     liftIO $ do
       WS.assertMatch_ (5 # Second) wsAlice $ \n -> do
@@ -695,7 +695,7 @@ addRemoteUser = do
               SomeConversationAction (sing @'ConversationJoinTag) (ConversationJoin (qdee :| [qeve, qflo]) roleNameWireMember)
           }
   WS.bracketRN c (map qUnqualified [qalice, qcharlie, qdee, qflo]) $ \[wsA, wsC, wsD, wsF] -> do
-    runFedClient @"on-conversation-updated" fedGalleyClient bdom cu
+    void $ runFedClient @"on-conversation-updated" fedGalleyClient bdom cu
     void . liftIO $ do
       WS.assertMatchN_ (5 # Second) [wsA, wsD] $
         wsAssertMemberJoinWithRole qconv qbob [qeve, qdee] roleNameWireMember