diff --git a/packages/crypto/src/index.ts b/packages/crypto/src/index.ts
index 9365daa2..925865b3 100644
--- a/packages/crypto/src/index.ts
+++ b/packages/crypto/src/index.ts
@@ -8,6 +8,7 @@ export {
   xchacha20NonceLength,
   Argon2id,
   Argon2idOptions,
+  isArgon2idOptions,
   Ed25519,
   Ed25519Keypair,
 } from "./libsodium";
diff --git a/packages/crypto/src/libsodium.ts b/packages/crypto/src/libsodium.ts
index a68274cc..0776a0c6 100644
--- a/packages/crypto/src/libsodium.ts
+++ b/packages/crypto/src/libsodium.ts
@@ -3,6 +3,7 @@
 //
 // libsodium.js API: https://gist.github.com/webmaster128/b2dbe6d54d36dd168c9fabf441b9b09c
 
+import { isNonNullObject } from "@cosmjs/utils";
 import sodium from "libsodium-wrappers";
 
 export interface Argon2idOptions {
@@ -24,6 +25,14 @@ export interface Argon2idOptions {
   readonly memLimitKib: number;
 }
 
+export function isArgon2idOptions(thing: unknown): thing is Argon2idOptions {
+  if (!isNonNullObject(thing)) return false;
+  if (typeof (thing as Argon2idOptions).outputLength !== "number") return false;
+  if (typeof (thing as Argon2idOptions).opsLimit !== "number") return false;
+  if (typeof (thing as Argon2idOptions).memLimitKib !== "number") return false;
+  return true;
+}
+
 export class Argon2id {
   public static async execute(
     password: string,
diff --git a/packages/crypto/types/index.d.ts b/packages/crypto/types/index.d.ts
index 9365daa2..925865b3 100644
--- a/packages/crypto/types/index.d.ts
+++ b/packages/crypto/types/index.d.ts
@@ -8,6 +8,7 @@ export {
   xchacha20NonceLength,
   Argon2id,
   Argon2idOptions,
+  isArgon2idOptions,
   Ed25519,
   Ed25519Keypair,
 } from "./libsodium";
diff --git a/packages/crypto/types/libsodium.d.ts b/packages/crypto/types/libsodium.d.ts
index 00437296..fbddb7f3 100644
--- a/packages/crypto/types/libsodium.d.ts
+++ b/packages/crypto/types/libsodium.d.ts
@@ -16,6 +16,7 @@ export interface Argon2idOptions {
    */
   readonly memLimitKib: number;
 }
+export declare function isArgon2idOptions(thing: unknown): thing is Argon2idOptions;
 export declare class Argon2id {
   static execute(password: string, salt: Uint8Array, options: Argon2idOptions): Promise<Uint8Array>;
 }
diff --git a/packages/sdk38/src/wallet.ts b/packages/sdk38/src/wallet.ts
index 0b7bba0a..f8e4b1ab 100644
--- a/packages/sdk38/src/wallet.ts
+++ b/packages/sdk38/src/wallet.ts
@@ -1,6 +1,6 @@
 import {
   Argon2id,
-  Argon2idOptions,
+  isArgon2idOptions,
   Random,
   Sha256,
   Sha512,
@@ -9,7 +9,6 @@ import {
   Xchacha20poly1305Ietf,
 } from "@cosmjs/crypto";
 import { toAscii } from "@cosmjs/encoding";
-import { assert } from "@cosmjs/utils";
 
 import { StdSignature } from "./types";
 
@@ -82,11 +81,8 @@ export interface KdfConfiguration {
 export async function executeKdf(password: string, configuration: KdfConfiguration): Promise<Uint8Array> {
   switch (configuration.algorithm) {
     case "argon2id": {
-      const { outputLength, opsLimit, memLimitKib } = configuration.params;
-      assert(typeof outputLength === "number");
-      assert(typeof opsLimit === "number");
-      assert(typeof memLimitKib === "number");
-      const options: Argon2idOptions = { outputLength, opsLimit, memLimitKib };
+      const options = configuration.params;
+      if (!isArgon2idOptions(options)) throw new Error("Invalid format of argon2id params");
       return Argon2id.execute(password, cosmjsSalt, options);
     }
     default: