diff --git a/chain/events/observer.go b/chain/events/observer.go
index 72b9deaee..446218585 100644
--- a/chain/events/observer.go
+++ b/chain/events/observer.go
@@ -125,7 +125,7 @@ func (o *observer) listenHeadChangesOnce(ctx context.Context) error {
 
 	for changes := range notifs {
 		if err := o.applyChanges(ctx, changes); err != nil {
-			return err
+			return xerrors.Errorf("failed to apply a change notification: %w", err)
 		}
 	}
 
diff --git a/chain/store/store.go b/chain/store/store.go
index 7343bdf9d..fd12b88a5 100644
--- a/chain/store/store.go
+++ b/chain/store/store.go
@@ -425,6 +425,11 @@ func (cs *ChainStore) MaybeTakeHeavierTipSet(ctx context.Context, ts *types.TipS
 	}
 
 	defer cs.heaviestLk.Unlock()
+
+	if ts.Equals(cs.heaviest) {
+		return nil
+	}
+
 	w, err := cs.weight(ctx, cs.StateBlockstore(), ts)
 	if err != nil {
 		return err