diff --git a/accounts/external/backend.go b/accounts/external/backend.go
index 42eaf661cc..d73fb06ad0 100644
--- a/accounts/external/backend.go
+++ b/accounts/external/backend.go
@@ -237,6 +237,7 @@ func (api *ExternalSigner) SignTx(account accounts.Account, tx *types.Transactio
 	}
 	if tx.Type() == types.BlobTxType {
 		args.BlobHashes = tx.BlobHashes()
+		args.BlobFeeCap = (*hexutil.Big)(tx.BlobGasFeeCap())
 		sidecar := tx.BlobTxSidecar()
 		if sidecar == nil {
 			return nil, errors.New("blobs must be present for signing")