diff --git a/signer/fourbyte/validation.go b/signer/fourbyte/validation.go
index 5ce8d3bac4..8bff011925 100644
--- a/signer/fourbyte/validation.go
+++ b/signer/fourbyte/validation.go
@@ -20,7 +20,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/signer/core/apitypes"