diff --git a/roomserver/query/query.go b/roomserver/query/query.go
index 32e37bfe6..7fe9dc980 100644
--- a/roomserver/query/query.go
+++ b/roomserver/query/query.go
@@ -598,10 +598,14 @@ func (r *RoomserverQueryAPI) isServerCurrentlyInRoom(ctx context.Context, server
 	return auth.IsAnyUserOnServerWithMembership(serverName, gmslEvents, gomatrixserverlib.Join), nil
 }
 
+// TODO: Remove this when we have tests to assert correctness of this function
+// nolint:gocyclo
 func (r *RoomserverQueryAPI) scanEventTree(
 	ctx context.Context, front []string, visited map[string]bool, limit int,
 	serverName gomatrixserverlib.ServerName,
-) (resultNIDs []types.EventNID, err error) {
+) ([]types.EventNID, error) {
+	var resultNIDs []types.EventNID
+	var err error
 	var allowed bool
 	var events []types.Event
 	var next []string
@@ -633,7 +637,7 @@ BFSLoop:
 		// Retrieve the events to process from the database.
 		events, err = r.DB.EventsFromIDs(ctx, front)
 		if err != nil {
-			return
+			return resultNIDs, err
 		}
 
 		if !checkedServerInRoom && len(events) > 0 {
@@ -668,7 +672,7 @@ BFSLoop:
 						util.GetLogger(ctx).WithField("server", serverName).WithField("event_id", pre).WithError(err).Error(
 							"Error checking if allowed to see event",
 						)
-						return
+						return resultNIDs, err
 					}
 
 					// If the event hasn't been seen before and the HS
@@ -686,7 +690,7 @@ BFSLoop:
 		front = next
 	}
 
-	return
+	return resultNIDs, err
 }
 
 // QueryStateAndAuthChain implements api.RoomserverQueryAPI
diff --git a/syncapi/routing/messages.go b/syncapi/routing/messages.go
index 1bf9ad339..5f2e4f171 100644
--- a/syncapi/routing/messages.go
+++ b/syncapi/routing/messages.go
@@ -428,9 +428,9 @@ func (r *messagesReq) serverToBackfillFrom(fromEventIDs []string) (gomatrixserve
 		// The rationale here is that the last event was unlikely to be sent by us, so poke the server who sent it.
 		// We shouldn't be doing this really, but as a heuristic it should work pretty well for now.
 		for _, e := range events {
-			_, srv, err := gomatrixserverlib.SplitID('@', e.Sender())
-			if err != nil {
-				util.GetLogger(r.ctx).WithError(err).Warn("Failed to extract domain from event sender")
+			_, srv, srverr := gomatrixserverlib.SplitID('@', e.Sender())
+			if srverr != nil {
+				util.GetLogger(r.ctx).WithError(srverr).Warn("Failed to extract domain from event sender")
 				continue
 			}
 			if srv != r.cfg.Matrix.ServerName {