diff --git a/lib/Federation/FederationManager.php b/lib/Federation/FederationManager.php
index 6b2b7ab8846..d81d1e34476 100644
--- a/lib/Federation/FederationManager.php
+++ b/lib/Federation/FederationManager.php
@@ -144,7 +144,7 @@ public function acceptRemoteRoomShare(IUser $user, int $shareId): Participant {
 				'actorId' => $user->getUID(),
 				'displayName' => $user->getDisplayName(),
 				'accessToken' => $invitation->getAccessToken(),
-				'remoteId' => $invitation->getRemoteAttendeeId(), // FIXME this seems unnecessary
+				'remoteId' => $invitation->getRemoteAttendeeId(),
 				'invitedCloudId' => $invitation->getLocalCloudId(),
 			]
 		];
diff --git a/lib/Service/RoomFormatter.php b/lib/Service/RoomFormatter.php
index 655ef3b46b9..251e63c7578 100644
--- a/lib/Service/RoomFormatter.php
+++ b/lib/Service/RoomFormatter.php
@@ -400,6 +400,10 @@ public function formatRoomV4(
 			}
 		}
 
+		if ($room->getRemoteServer() !== '') {
+			$roomData['attendeeId'] = (int) $attendee->getRemoteId();
+		}
+
 		return $roomData;
 	}