diff --git a/src/wallet-manager-evm.js b/src/wallet-manager-evm.js
index 60a89da..859b6fc 100644
--- a/src/wallet-manager-evm.js
+++ b/src/wallet-manager-evm.js
@@ -27,6 +27,7 @@ import SeedSignerEvm from './signers/seed-signer-evm.js'
 /** @typedef {import('ethers').Provider} Provider */
 
 /** @typedef {import("@tetherto/wdk-wallet").FeeRates} FeeRates */
+/** @typedef {import("@tetherto/wdk-wallet").ISigner} ISigner */
 /** @typedef {import("@tetherto/wdk-wallet").SignerError} SignerError */
 
 /** @typedef {import('./wallet-account-evm.js').EvmWalletConfig} EvmWalletConfig */
@@ -56,7 +57,7 @@ export default class WalletManagerEvm extends WalletManager {
    * derive child accounts); non-derivable signers (e.g. private-key signers) are not allowed
    * as the default but may be registered by name via {@link addSigner} - If not adding to your global account managment for using just one non derivable signer create a standalone account.
    *
-   * @param {string|Uint8Array|ISignerEvm} seedOrSigner - A BIP-39 seed phrase, seed bytes, or a root signer.
+   * @param {string|Uint8Array|ISigner} seedOrSigner - A BIP-39 seed phrase, seed bytes, or a root signer. Root signers must be derivable — non-derivable signers (e.g. private-key signers) can only be registered by name via {@link addSigner}.
    * @param {EvmWalletConfig} [config] - The configuration object.
    */
   constructor (seedOrSigner, config = {}) {
diff --git a/tests/wallet-manager-evm.test.js b/tests/wallet-manager-evm.test.js
index 05e117a..737abe7 100644
--- a/tests/wallet-manager-evm.test.js
+++ b/tests/wallet-manager-evm.test.js
@@ -29,6 +29,13 @@ describe('WalletManagerEvm', () => {
       expect(() => new WalletManagerEvm(new PrivateKeySignerEvm(PRIVATE_KEY))) // eslint-disable-line no-new
         .toThrow('The default signer must be derivable.')
     })
+
+    test('should throw if the default signer is a bare ISigner without isDerivable', () => {
+      const bareSigner = { derive: async () => {}, signTransaction: async () => {}, getAddress: async () => '0x0', dispose: () => {} }
+
+      expect(() => new WalletManagerEvm(bareSigner)) // eslint-disable-line no-new
+        .toThrow('The default signer must be derivable.')
+    })
   })
 
   describe('getAccount', () => {
diff --git a/types/src/wallet-manager-evm.d.ts b/types/src/wallet-manager-evm.d.ts
index 183bb1c..dac7f53 100644
--- a/types/src/wallet-manager-evm.d.ts
+++ b/types/src/wallet-manager-evm.d.ts
@@ -1,5 +1,6 @@
 /** @typedef {import('ethers').Provider} Provider */
 /** @typedef {import("@tetherto/wdk-wallet").FeeRates} FeeRates */
+/** @typedef {import("@tetherto/wdk-wallet").ISigner} ISigner */
 /** @typedef {import('./wallet-account-evm.js').EvmWalletConfig} EvmWalletConfig */
 export default class WalletManagerEvm extends WalletManager {
     /**
@@ -24,10 +25,10 @@ export default class WalletManagerEvm extends WalletManager {
      * derive child accounts); non-derivable signers (e.g. private-key signers) are not allowed
      * as the default but may be registered by name via {@link addSigner} - If not adding to your global account managment for using just one non derivable signer create a standalone account.
      *
-     * @param {string|Uint8Array|ISignerEvm} seedOrSigner - A BIP-39 seed phrase, seed bytes, or a root signer.
+     * @param {string|Uint8Array|ISigner} seedOrSigner - A BIP-39 seed phrase, seed bytes, or a root signer. Root signers must be derivable — non-derivable signers (e.g. private-key signers) can only be registered by name via {@link addSigner}.
      * @param {EvmWalletConfig} [config] - The configuration object.
      */
-    constructor(seedOrSigner: string | Uint8Array | ISignerEvm, config?: EvmWalletConfig);
+    constructor(seedOrSigner: string | Uint8Array | ISigner, config?: EvmWalletConfig);
     /**
      * An ethers provider to interact with a node of the blockchain.
      *
@@ -81,6 +82,7 @@ export default class WalletManagerEvm extends WalletManager {
 export type ISignerEvm = import("./signers/seed-signer-evm.js").ISignerEvm;
 export type Provider = import("ethers").Provider;
 export type FeeRates = import("@tetherto/wdk-wallet").FeeRates;
+export type ISigner = import("@tetherto/wdk-wallet").ISigner;
 export type EvmWalletConfig = import("./wallet-account-evm.js").EvmWalletConfig;
 import WalletManager from '@tetherto/wdk-wallet';
 import WalletAccountEvm from './wallet-account-evm.js';