diff --git a/src/sig/SignatureLib.sol b/src/sig/SignatureLib.sol
index b1a63a3..448950f 100644
--- a/src/sig/SignatureLib.sol
+++ b/src/sig/SignatureLib.sol
@@ -45,6 +45,13 @@ library SignatureLib {
     uint8 internal constant WEBAUTHN_FLAG_UP = 0x01; // user present
     uint8 internal constant WEBAUTHN_FLAG_UV = 0x04; // user verified
 
+    /*//////////////////////////////////////////////////////////////
+                                   ERRORS
+    //////////////////////////////////////////////////////////////*/
+
+    /// @notice Thrown when `webauthnData` is shorter than the 37-byte authenticatorData prefix.
+    error WebAuthnDataTooShort();
+
     /*//////////////////////////////////////////////////////////////
                               LOW-S NORMALIZATION
     //////////////////////////////////////////////////////////////*/
@@ -150,7 +157,7 @@ library SignatureLib {
     /// @dev `sha256(authenticatorData || sha256(clientDataJSON))`.
     function webAuthnMessageHash(bytes memory webauthnData) internal pure returns (bytes32) {
         // First 37 bytes are authenticatorData (no extensions, since the precompile rejects ED).
-        require(webauthnData.length >= 37, "SignatureLib: webauthnData too short");
+        if (webauthnData.length < 37) revert WebAuthnDataTooShort();
         bytes memory authData = new bytes(37);
         bytes memory clientDataJSON = new bytes(webauthnData.length - 37);
         for (uint256 i = 0; i < 37; i++) {
diff --git a/src/tx/Eip1559TransactionLib.sol b/src/tx/Eip1559TransactionLib.sol
index 87b643e..eacb0b5 100644
--- a/src/tx/Eip1559TransactionLib.sol
+++ b/src/tx/Eip1559TransactionLib.sol
@@ -25,9 +25,12 @@ library Eip1559TransactionLib {
     /// @notice EIP-1559 transaction type prefix.
     uint8 internal constant TX_TYPE = 0x02;
 
+    /// @notice Thrown when `block.chainid` does not fit in a `uint64`.
+    error ChainIdExceedsUint64();
+
     /// @notice Creates a new EIP-1559 transaction with default values.
     function create() internal view returns (Eip1559Transaction memory tx_) {
-        require(block.chainid <= type(uint64).max, "chain ID exceeds uint64");
+        if (block.chainid > type(uint64).max) revert ChainIdExceedsUint64();
         // Safe after the explicit range check above.
         // forge-lint: disable-next-line(unsafe-typecast)
         tx_.chainId = uint64(block.chainid);
diff --git a/src/tx/Eip7702TransactionLib.sol b/src/tx/Eip7702TransactionLib.sol
index f0d3dd0..5620054 100644
--- a/src/tx/Eip7702TransactionLib.sol
+++ b/src/tx/Eip7702TransactionLib.sol
@@ -39,9 +39,12 @@ library Eip7702TransactionLib {
     /// @notice EIP-7702 authorization magic for signing.
     uint8 internal constant AUTH_MAGIC = 0x05;
 
+    /// @notice Thrown when `block.chainid` does not fit in a `uint64`.
+    error ChainIdExceedsUint64();
+
     /// @notice Creates a new EIP-7702 transaction with default values.
     function create() internal view returns (Eip7702Transaction memory tx_) {
-        require(block.chainid <= type(uint64).max, "chain ID exceeds uint64");
+        if (block.chainid > type(uint64).max) revert ChainIdExceedsUint64();
         // Safe after the explicit range check above.
         // forge-lint: disable-next-line(unsafe-typecast)
         tx_.chainId = uint64(block.chainid);
diff --git a/src/tx/TempoTransactionLib.sol b/src/tx/TempoTransactionLib.sol
index 0287257..fcfbd91 100644
--- a/src/tx/TempoTransactionLib.sol
+++ b/src/tx/TempoTransactionLib.sol
@@ -52,6 +52,9 @@ library TempoTransactionLib {
     /// @notice Tempo transaction type prefix.
     uint8 internal constant TX_TYPE = 0x76;
 
+    /// @notice Thrown when a fee payer signature is not exactly 65 bytes.
+    error InvalidFeePayerSignatureLength();
+
     /// @notice Creates a new Tempo transaction with default values.
     function create() internal pure returns (TempoTransaction memory tx_) {
         tx_.gasLimit = 21000;
@@ -431,7 +434,7 @@ library TempoTransactionLib {
 
     /// @notice Encodes fee payer signature as RLP list [v, r, s]
     function _encodeFeePayerSignature(bytes memory sig) private pure returns (bytes memory) {
-        require(sig.length == 65, "Invalid fee payer signature length");
+        if (sig.length != 65) revert InvalidFeePayerSignatureLength();
 
         // Parse signature: first 32 bytes = r, next 32 = s, last byte = v
         bytes32 r = bytes32(0);