diff --git a/packages/keyring-api/CHANGELOG.md b/packages/keyring-api/CHANGELOG.md
index d5a27d9c6..bb2aaf599 100644
--- a/packages/keyring-api/CHANGELOG.md
+++ b/packages/keyring-api/CHANGELOG.md
@@ -7,6 +7,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `EthAddressStrictStruct` struct and `EthAddressStrict` types ([#465](https://github.com/MetaMask/accounts/pull/465))
+  - This is a stricter variant of `EthAddressStruct` which uses `Hex` instead of `string` for its inferred type.
+
+### Changed
+
+- Re-use `string` for ERC4337 address-like fields ([#465](https://github.com/MetaMask/accounts/pull/465))
+  - This change reverts that and keeps using `string` for all address-like types.
+  - Changes in [#405](https://github.com/MetaMask/accounts/pull/405) updated the associated type for `EthAddressStruct` from `string` to `Hex`, this was actually a small breaking change that went unnoticed and that would require some effort to adapt in upstream clients/controllers, for this reason, we are undoing this change for now.
+  - Version [21.4.0] will be marked as **YANKED**, consumers are expected to use this new version that reverts this breaking change.
+
 ## [21.4.0]
 
 ### Added
diff --git a/packages/keyring-api/src/eth/rpc/params.ts b/packages/keyring-api/src/eth/rpc/params.ts
index 2331f3818..697fc3d65 100644
--- a/packages/keyring-api/src/eth/rpc/params.ts
+++ b/packages/keyring-api/src/eth/rpc/params.ts
@@ -23,7 +23,11 @@ import {
   unknown,
 } from '@metamask/superstruct';
 
-import { EthAddressStruct, EthBytesStruct } from '../types';
+import {
+  EthAddressStrictStruct,
+  EthAddressStruct,
+  EthBytesStruct,
+} from '../types';
 
 /**
  * A struct for validating Ethereum transaction data.
@@ -118,7 +122,7 @@ export type EthEncryptedData = Infer<typeof EthEncryptedDataStruct>;
  */
 export const EthEip7702AuthorizationStruct = tuple([
   number(), // chainId
-  EthAddressStruct, // address (contract to delegate to)
+  EthAddressStrictStruct, // address (contract to delegate to)
   number(), // nonce
 ]);
 
diff --git a/packages/keyring-api/src/eth/types.ts b/packages/keyring-api/src/eth/types.ts
index 12c586631..02f6e39ed 100644
--- a/packages/keyring-api/src/eth/types.ts
+++ b/packages/keyring-api/src/eth/types.ts
@@ -12,9 +12,12 @@ import {
 
 export const EthBytesStruct = definePattern('EthBytes', /^0x[0-9a-f]*$/iu);
 
-export const EthAddressStruct = definePattern<Hex>(
-  'EthAddress',
-  /^0x[0-9a-f]{40}$/iu,
+const ETH_ADDRESS_REGEX = /^0x[0-9a-f]{40}$/iu;
+export const EthAddressStruct = definePattern('EthAddress', ETH_ADDRESS_REGEX);
+// Stricter struct that uses `Hex` as final type.
+export const EthAddressStrictStruct = definePattern<Hex>(
+  'EthAddressStrict',
+  ETH_ADDRESS_REGEX,
 );
 
 export const EthUint256Struct = definePattern(