diff --git a/internal/ethapi/transaction_args.go b/internal/ethapi/transaction_args.go
index c4322fcbf8..3ecc384210 100644
--- a/internal/ethapi/transaction_args.go
+++ b/internal/ethapi/transaction_args.go
@@ -102,7 +102,7 @@ type sidecarConfig struct {
 
 // setDefaults fills in default values for unspecified tx fields.
 func (args *TransactionArgs) setDefaults(ctx context.Context, b Backend, config sidecarConfig) error {
-	if err := args.validateTxType(); err != nil {
+	if err := args.validateTxTypeSupported(); err != nil {
 		return err
 	}
 	if err := args.setBlobTxSidecar(ctx, config); err != nil {
@@ -180,6 +180,9 @@ func (args *TransactionArgs) setDefaults(ctx context.Context, b Backend, config
 	} else {
 		args.ChainID = (*hexutil.Big)(want)
 	}
+	if err := args.validateTxTypeMatch(types.LegacyTxType); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -394,7 +397,7 @@ func (args *TransactionArgs) setBlobTxSidecar(ctx context.Context, config sideca
 // CallDefaults sanitizes the transaction arguments, often filling in zero values,
 // for the purpose of eth_call class of RPC methods.
 func (args *TransactionArgs) CallDefaults(globalGasCap uint64, baseFee *big.Int, chainID *big.Int) error {
-	if err := args.validateTxType(); err != nil {
+	if err := args.validateTxTypeSupported(); err != nil {
 		return err
 	}
 	// Reject invalid combinations of pre- and post-1559 fee styles
@@ -443,11 +446,14 @@ func (args *TransactionArgs) CallDefaults(globalGasCap uint64, baseFee *big.Int,
 	if args.BlobFeeCap == nil && args.BlobHashes != nil {
 		args.BlobFeeCap = new(hexutil.Big)
 	}
+	if err := args.validateTxTypeMatch(types.LegacyTxType); err != nil {
+		return err
+	}
 
 	return nil
 }
 
-func (args *TransactionArgs) validateTxType() error {
+func (args *TransactionArgs) validateTxTypeSupported() error {
 	if args.Type == nil {
 		return nil
 	}
@@ -459,6 +465,21 @@ func (args *TransactionArgs) validateTxType() error {
 	}
 }
 
+func (args *TransactionArgs) validateTxTypeMatch(defaultType int) error {
+	if args.Type == nil {
+		return nil
+	}
+	// Blob txs cannot be contract creations. ToTransaction assumes this invariant.
+	if args.BlobHashes != nil && args.To == nil {
+		return errors.New(`missing "to" in blob transaction`)
+	}
+	inferred := args.ToTransaction(defaultType).Type()
+	if uint64(*args.Type) != uint64(inferred) {
+		return fmt.Errorf("transaction type mismatch (requested=%d inferred=%d)", uint64(*args.Type), inferred)
+	}
+	return nil
+}
+
 // ToMessage converts the transaction arguments to the Message type used by the
 // core evm. This method is used in calls and traces that do not require a real
 // live transaction.
diff --git a/internal/ethapi/transaction_args_test.go b/internal/ethapi/transaction_args_test.go
index 310fddcabb..d13daa3738 100644
--- a/internal/ethapi/transaction_args_test.go
+++ b/internal/ethapi/transaction_args_test.go
@@ -290,6 +290,45 @@ func TestTransactionArgsRejectUnsupportedTypeInSetDefaults(t *testing.T) {
 	}
 }
 
+func TestTransactionArgsRejectTypeMismatchInCallDefaults(t *testing.T) {
+	t.Parallel()
+
+	requestedLegacy := hexutil.Uint64(types.LegacyTxType)
+	args := &TransactionArgs{
+		Type:        &requestedLegacy,
+		MaxFeePerGas: (*hexutil.Big)(big.NewInt(2)),
+	}
+	err := args.CallDefaults(0, big.NewInt(1), big.NewInt(1))
+	if err == nil {
+		t.Fatal("expected type mismatch error")
+	}
+	if err.Error() != "transaction type mismatch (requested=0 inferred=2)" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestTransactionArgsRejectTypeMismatchInSetDefaults(t *testing.T) {
+	t.Parallel()
+
+	requestedDynamic := hexutil.Uint64(types.DynamicFeeTxType)
+	gas := hexutil.Uint64(21000)
+	gasPrice := (*hexutil.Big)(big.NewInt(1))
+	to := common.Address{0x1}
+	args := &TransactionArgs{
+		To:       &to,
+		Gas:      &gas,
+		GasPrice: gasPrice,
+		Type:     &requestedDynamic,
+	}
+	err := args.setDefaults(context.Background(), newBackendMock(), sidecarConfig{})
+	if err == nil {
+		t.Fatal("expected type mismatch error")
+	}
+	if err.Error() != "transaction type mismatch (requested=2 inferred=0)" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
 type backendMock struct {
 	current *types.Header
 	config  *params.ChainConfig