diff --git a/roomserver/internal/perform_join.go b/roomserver/internal/perform_join.go
index 502fe3833..99e10d974 100644
--- a/roomserver/internal/perform_join.go
+++ b/roomserver/internal/perform_join.go
@@ -116,7 +116,7 @@ func (r *RoomserverInternalAPI) performJoinRoomByID(
 	if req.Content == nil {
 		req.Content = map[string]interface{}{}
 	}
-	req.Content["membership"] = "join"
+	req.Content["membership"] = gomatrixserverlib.Join
 	if err = eb.SetContent(req.Content); err != nil {
 		return fmt.Errorf("eb.SetContent: %w", err)
 	}
@@ -145,7 +145,7 @@ func (r *RoomserverInternalAPI) performJoinRoomByID(
 		for _, se := range buildRes.StateEvents {
 			if membership, merr := se.Membership(); merr == nil {
 				if se.StateKey() != nil && *se.StateKey() == *event.StateKey() {
-					alreadyJoined = (membership == "join")
+					alreadyJoined = (membership == gomatrixserverlib.Join)
 					break
 				}
 			}
diff --git a/roomserver/internal/perform_leave.go b/roomserver/internal/perform_leave.go
index 1d6d47145..eb41fe47e 100644
--- a/roomserver/internal/perform_leave.go
+++ b/roomserver/internal/perform_leave.go
@@ -70,7 +70,7 @@ func (r *RoomserverInternalAPI) performLeaveRoomByID(
 	if err != nil {
 		return fmt.Errorf("Error getting membership: %w", err)
 	}
-	if membership != "join" {
+	if membership != gomatrixserverlib.Join {
 		// TODO: should be able to handle "invite" in this case too, if
 		// it's a case of kicking or banning or such
 		return fmt.Errorf("User %q is not joined to the room (membership is %q)", req.UserID, membership)