diff --git a/simplex/epoch.go b/simplex/epoch.go
index 569f33ae..c1c48a19 100644
--- a/simplex/epoch.go
+++ b/simplex/epoch.go
@@ -166,7 +166,7 @@ func (e *Epoch) HandleMessage(msg *common.Message, from common.NodeID) error {
 	}
 
 	_, known := e.validatorsToPKs[string(from)]
-	if !known {
+	if !known || e.isEpochSealed() {
 		e.Logger.Debug("Received message from a non-validator node", zap.Stringer("nodeID", from))
 		switch {
 		case msg.ReplicationRequest != nil && e.ReplicationEnabled:
@@ -1466,6 +1466,7 @@ func (e *Epoch) indexFinalizations(startRound uint64) error {
 }
 
 func (e *Epoch) indexFinalization(block common.VerifiedBlock, finalization common.Finalization) error {
+	// index only if the epoch is not sealed
 	if err := e.Storage.Index(e.finishCtx, block, finalization); err != nil {
 		return err
 	}
@@ -1473,6 +1474,7 @@ func (e *Epoch) indexFinalization(block common.VerifiedBlock, finalization commo
 		zap.Uint64("round", finalization.Finalization.Round),
 		zap.Uint64("sequence", finalization.Finalization.Seq),
 		zap.Stringer("digest", finalization.Finalization.Digest))
+
 	e.lastBlock = &common.VerifiedFinalizedBlock{
 		VerifiedBlock: block,
 		Finalization:  finalization,