diff --git a/ethclient/ethclient.go b/ethclient/ethclient.go
index eb9dd86b45..09ee0271d6 100644
--- a/ethclient/ethclient.go
+++ b/ethclient/ethclient.go
@@ -23,6 +23,7 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
+	"strconv"
 
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
@@ -194,18 +195,22 @@ func (ec *Client) TransactionByHash(ctx context.Context, hash common.Hash) (tx *
 }
 
 // BlockNumberByTransactionHash returns block number for the transaction with the given hash.
-func (ec *Client) BlockNumberByTransactionHash(ctx context.Context, hash common.Hash) (blockNumber *string, err error) {
+func (ec *Client) BlockNumberByTransactionHash(ctx context.Context, hash common.Hash) (blockNumber uint64, err error) {
 	var json *rpcTransaction
 	err = ec.c.CallContext(ctx, &json, "eth_getTransactionByHash", hash)
 	if err != nil {
-		return nil, err
+		return 0, err
 	} else if json == nil {
-		return nil, ethereum.NotFound
+		return 0, ethereum.NotFound
 	} else if _, r, _ := json.tx.RawSignatureValues(); r == nil {
-		return nil, fmt.Errorf("server returned transaction without signature")
+		return 0, fmt.Errorf("server returned transaction without signature")
 	}
 	setSenderFromServer(json.tx, json.From, json.BlockHash)
-	return json.BlockNumber, nil
+	blockNumber, err = strconv.ParseUint(*json.BlockNumber, 0, 64)
+	if err != nil {
+		return 0, err
+	}
+	return blockNumber, nil
 }
 
 // TransactionSender returns the sender address of the given transaction. The transaction