diff --git a/core/types/transaction.go b/core/types/transaction.go
index 7b53cac2c..ba3d5de91 100644
--- a/core/types/transaction.go
+++ b/core/types/transaction.go
@@ -234,7 +234,7 @@ func (tx *Transaction) AsMessage(s Signer) (Message, error) {
 }
 
 // WithSignature returns a new transaction with the given signature.
-// This signature needs to be formatted as described in the yellow paper (v+27).
+// This signature needs to be in the [R || S || V] format where V is 0 or 1.
 func (tx *Transaction) WithSignature(signer Signer, sig []byte) (*Transaction, error) {
 	r, s, v, err := signer.SignatureValues(tx, sig)
 	if err != nil {