diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index bb0dd042ab..d11d38883b 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -1865,7 +1865,7 @@ func (api *TransactionAPI) SignTransaction(ctx context.Context, args Transaction
 	// If the transaction-to-sign was a blob transaction, then the signed one
 	// no longer retains the blobs, only the blob hashes. In this step, we need
 	// to put back the blob(s).
-	if args.IsEIP4844() {
+	if args.Blobs != nil {
 		signed = signed.WithBlobTxSidecar(types.NewBlobTxSidecar(sidecarVersion, args.Blobs, args.Commitments, args.Proofs))
 	}
 	data, err := signed.MarshalBinary()
diff --git a/internal/ethapi/api_test.go b/internal/ethapi/api_test.go
index 62e9979d3d..0e655786a8 100644
--- a/internal/ethapi/api_test.go
+++ b/internal/ethapi/api_test.go
@@ -2698,10 +2698,15 @@ func TestSignBlobTransaction(t *testing.T) {
 		t.Fatalf("failed to fill tx defaults: %v\n", err)
 	}
 
-	_, err = api.SignTransaction(context.Background(), argsFromTransaction(res.Tx, b.acc.Address))
+	result, err := api.SignTransaction(context.Background(), argsFromTransaction(res.Tx, b.acc.Address))
 	if err != nil {
 		t.Fatalf("should not fail on blob transaction")
 	}
+	// When no blobs are provided (only blob hashes), the signed transaction
+	// should not have an empty sidecar attached.
+	if result.Tx.BlobTxSidecar() != nil {
+		t.Fatal("signed transaction should not have a sidecar when no blobs were provided")
+	}
 }
 
 func TestSendBlobTransaction(t *testing.T) {