diff --git a/txpool/pool.go b/txpool/pool.go
index 7dec14895..791298679 100644
--- a/txpool/pool.go
+++ b/txpool/pool.go
@@ -822,7 +822,7 @@ func (p *TxPool) ValidateSerializedTxn(serializedTxn []byte) error {
 		txMaxSize = 4 * txSlotSize // 128KB
 	)
 	if len(serializedTxn) > txMaxSize {
-		return fmt.Errorf(RLPTooLong.String())
+		return types.ErrRlpTooBig
 	}
 	return nil
 }
diff --git a/txpool/txpool_grpc_server.go b/txpool/txpool_grpc_server.go
index fd12a9235..4484ea325 100644
--- a/txpool/txpool_grpc_server.go
+++ b/txpool/txpool_grpc_server.go
@@ -240,7 +240,7 @@ func mapDiscardReasonToProto(reason DiscardReason) txpool_proto.ImportResult {
 		return txpool_proto.ImportResult_ALREADY_EXISTS
 	case UnderPriced, ReplaceUnderpriced, FeeTooLow:
 		return txpool_proto.ImportResult_FEE_TOO_LOW
-	case InvalidSender, NegativeValue, OversizedData, InitCodeTooLarge:
+	case InvalidSender, NegativeValue, OversizedData, InitCodeTooLarge, RLPTooLong:
 		return txpool_proto.ImportResult_INVALID
 	default:
 		return txpool_proto.ImportResult_INTERNAL_ERROR