diff --git a/core/types/gen_authorization.go b/core/types/gen_authorization.go
index 45409f0624..b598b64ff7 100644
--- a/core/types/gen_authorization.go
+++ b/core/types/gen_authorization.go
@@ -5,10 +5,10 @@ package types
 import (
 	"encoding/json"
 	"errors"
-	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/holiman/uint256"
 )
 
 var _ = (*authorizationMarshaling)(nil)
@@ -20,16 +20,16 @@ func (a Authorization) MarshalJSON() ([]byte, error) {
 		Address common.Address `json:"address" gencodec:"required"`
 		Nonce   hexutil.Uint64 `json:"nonce" gencodec:"required"`
 		V       hexutil.Uint64 `json:"v" gencodec:"required"`
-		R       *hexutil.Big   `json:"r" gencodec:"required"`
-		S       *hexutil.Big   `json:"s" gencodec:"required"`
+		R       uint256.Int    `json:"r" gencodec:"required"`
+		S       uint256.Int    `json:"s" gencodec:"required"`
 	}
 	var enc Authorization
 	enc.ChainID = hexutil.Uint64(a.ChainID)
 	enc.Address = a.Address
 	enc.Nonce = hexutil.Uint64(a.Nonce)
 	enc.V = hexutil.Uint64(a.V)
-	enc.R = (*hexutil.Big)(a.R)
-	enc.S = (*hexutil.Big)(a.S)
+	enc.R = a.R
+	enc.S = a.S
 	return json.Marshal(&enc)
 }
 
@@ -40,8 +40,8 @@ func (a *Authorization) UnmarshalJSON(input []byte) error {
 		Address *common.Address `json:"address" gencodec:"required"`
 		Nonce   *hexutil.Uint64 `json:"nonce" gencodec:"required"`
 		V       *hexutil.Uint64 `json:"v" gencodec:"required"`
-		R       *hexutil.Big    `json:"r" gencodec:"required"`
-		S       *hexutil.Big    `json:"s" gencodec:"required"`
+		R       *uint256.Int    `json:"r" gencodec:"required"`
+		S       *uint256.Int    `json:"s" gencodec:"required"`
 	}
 	var dec Authorization
 	if err := json.Unmarshal(input, &dec); err != nil {
@@ -66,10 +66,10 @@ func (a *Authorization) UnmarshalJSON(input []byte) error {
 	if dec.R == nil {
 		return errors.New("missing required field 'r' for Authorization")
 	}
-	a.R = (*big.Int)(dec.R)
+	a.R = *dec.R
 	if dec.S == nil {
 		return errors.New("missing required field 's' for Authorization")
 	}
-	a.S = (*big.Int)(dec.S)
+	a.S = *dec.S
 	return nil
 }
diff --git a/core/types/tx_setcode.go b/core/types/tx_setcode.go
index f2e3bd7550..6e0665fa68 100644
--- a/core/types/tx_setcode.go
+++ b/core/types/tx_setcode.go
@@ -75,8 +75,8 @@ type Authorization struct {
 	Address common.Address `json:"address" gencodec:"required"`
 	Nonce   uint64         `json:"nonce" gencodec:"required"`
 	V       uint8          `json:"v" gencodec:"required"`
-	R       *big.Int       `json:"r" gencodec:"required"`
-	S       *big.Int       `json:"s" gencodec:"required"`
+	R       uint256.Int    `json:"r" gencodec:"required"`
+	S       uint256.Int    `json:"s" gencodec:"required"`
 }
 
 // field type overrides for gencodec
@@ -84,8 +84,6 @@ type authorizationMarshaling struct {
 	ChainID hexutil.Uint64
 	Nonce   hexutil.Uint64
 	V       hexutil.Uint64
-	R       *hexutil.Big
-	S       *hexutil.Big
 }
 
 // SignAuth signs the provided authorization.
@@ -114,12 +112,12 @@ func (a *Authorization) withSignature(sig []byte) Authorization {
 		Address: a.Address,
 		Nonce:   a.Nonce,
 		V:       sig[64],
-		R:       r,
-		S:       s,
+		R:       *uint256.MustFromBig(r),
+		S:       *uint256.MustFromBig(s),
 	}
 }
 
-// Authority recovers the authorizing
+// Authority recovers the the authorizing account of an authorization.
 func (a Authorization) Authority() (common.Address, error) {
 	sighash := prefixedRlpHash(
 		0x05,
@@ -128,17 +126,16 @@ func (a Authorization) Authority() (common.Address, error) {
 			a.Address,
 			a.Nonce,
 		})
-	if !crypto.ValidateSignatureValues(a.V, a.R, a.S, true) {
+	if !crypto.ValidateSignatureValues(a.V, a.R.ToBig(), a.S.ToBig(), true) {
 		return common.Address{}, ErrInvalidSig
 	}
 	// encode the signature in uncompressed format
-	r, s := a.R.Bytes(), a.S.Bytes()
-	sig := make([]byte, crypto.SignatureLength)
-	copy(sig[32-len(r):32], r)
-	copy(sig[64-len(s):64], s)
+	var sig [crypto.SignatureLength]byte
+	a.R.SetBytes32(sig[:32])
+	a.R.SetBytes32(sig[32:64])
 	sig[64] = a.V
 	// recover the public key from the signature
-	pub, err := crypto.Ecrecover(sighash[:], sig)
+	pub, err := crypto.Ecrecover(sighash[:], sig[:])
 	if err != nil {
 		return common.Address{}, err
 	}
diff --git a/tests/gen_stauthorization.go b/tests/gen_stauthorization.go
index fbafd6fdea..f40d32c721 100644
--- a/tests/gen_stauthorization.go
+++ b/tests/gen_stauthorization.go
@@ -5,10 +5,10 @@ package tests
 import (
 	"encoding/json"
 	"errors"
-	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/math"
+	"github.com/holiman/uint256"
 )
 
 var _ = (*stAuthorizationMarshaling)(nil)
@@ -17,19 +17,19 @@ var _ = (*stAuthorizationMarshaling)(nil)
 func (s stAuthorization) MarshalJSON() ([]byte, error) {
 	type stAuthorization struct {
 		ChainID math.HexOrDecimal64
-		Address common.Address        `json:"address" gencodec:"required"`
-		Nonce   math.HexOrDecimal64   `json:"nonce" gencodec:"required"`
-		V       math.HexOrDecimal64   `json:"v" gencodec:"required"`
-		R       *math.HexOrDecimal256 `json:"r" gencodec:"required"`
-		S       *math.HexOrDecimal256 `json:"s" gencodec:"required"`
+		Address common.Address      `json:"address" gencodec:"required"`
+		Nonce   math.HexOrDecimal64 `json:"nonce" gencodec:"required"`
+		V       math.HexOrDecimal64 `json:"v" gencodec:"required"`
+		R       uint256.Int         `json:"r" gencodec:"required"`
+		S       uint256.Int         `json:"s" gencodec:"required"`
 	}
 	var enc stAuthorization
 	enc.ChainID = math.HexOrDecimal64(s.ChainID)
 	enc.Address = s.Address
 	enc.Nonce = math.HexOrDecimal64(s.Nonce)
 	enc.V = math.HexOrDecimal64(s.V)
-	enc.R = (*math.HexOrDecimal256)(s.R)
-	enc.S = (*math.HexOrDecimal256)(s.S)
+	enc.R = s.R
+	enc.S = s.S
 	return json.Marshal(&enc)
 }
 
@@ -37,11 +37,11 @@ func (s stAuthorization) MarshalJSON() ([]byte, error) {
 func (s *stAuthorization) UnmarshalJSON(input []byte) error {
 	type stAuthorization struct {
 		ChainID *math.HexOrDecimal64
-		Address *common.Address       `json:"address" gencodec:"required"`
-		Nonce   *math.HexOrDecimal64  `json:"nonce" gencodec:"required"`
-		V       *math.HexOrDecimal64  `json:"v" gencodec:"required"`
-		R       *math.HexOrDecimal256 `json:"r" gencodec:"required"`
-		S       *math.HexOrDecimal256 `json:"s" gencodec:"required"`
+		Address *common.Address      `json:"address" gencodec:"required"`
+		Nonce   *math.HexOrDecimal64 `json:"nonce" gencodec:"required"`
+		V       *math.HexOrDecimal64 `json:"v" gencodec:"required"`
+		R       *uint256.Int         `json:"r" gencodec:"required"`
+		S       *uint256.Int         `json:"s" gencodec:"required"`
 	}
 	var dec stAuthorization
 	if err := json.Unmarshal(input, &dec); err != nil {
@@ -65,10 +65,10 @@ func (s *stAuthorization) UnmarshalJSON(input []byte) error {
 	if dec.R == nil {
 		return errors.New("missing required field 'r' for stAuthorization")
 	}
-	s.R = (*big.Int)(dec.R)
+	s.R = *dec.R
 	if dec.S == nil {
 		return errors.New("missing required field 's' for stAuthorization")
 	}
-	s.S = (*big.Int)(dec.S)
+	s.S = *dec.S
 	return nil
 }
diff --git a/tests/state_test_util.go b/tests/state_test_util.go
index 6a3ac952ed..a26d2da7b5 100644
--- a/tests/state_test_util.go
+++ b/tests/state_test_util.go
@@ -144,8 +144,8 @@ type stAuthorization struct {
 	Address common.Address `json:"address" gencodec:"required"`
 	Nonce   uint64         `json:"nonce" gencodec:"required"`
 	V       uint8          `json:"v" gencodec:"required"`
-	R       *big.Int       `json:"r" gencodec:"required"`
-	S       *big.Int       `json:"s" gencodec:"required"`
+	R       uint256.Int    `json:"r" gencodec:"required"`
+	S       uint256.Int    `json:"s" gencodec:"required"`
 }
 
 // field type overrides for gencodec
@@ -153,8 +153,6 @@ type stAuthorizationMarshaling struct {
 	ChainID math.HexOrDecimal64
 	Nonce   math.HexOrDecimal64
 	V       math.HexOrDecimal64
-	R       *math.HexOrDecimal256
-	S       *math.HexOrDecimal256
 }
 
 // GetChainConfig takes a fork definition and returns a chain config.