diff --git a/packages/client/src/helpers/authz.ts b/packages/client/src/helpers/authz.ts
new file mode 100644
index 00000000..bc6cd49d
--- /dev/null
+++ b/packages/client/src/helpers/authz.ts
@@ -0,0 +1,38 @@
+import type { AminoMsg } from '@cosmjs/amino'
+import {
+  type AminoConverter,
+  AminoTypes,
+  createDefaultAminoConverters,
+} from '@cosmjs/stargate'
+
+import { MsgExec } from '@/codec/cosmos/authz/v1beta1/tx'
+import { MessageTypeUrls } from '@/enums'
+
+// TODO: https://github.com/likecoin/iscn-js/blob/1ac7fb6f3b568e0d35e598442769a283c669c34b/src/messages/authz.ts#L98
+export function createAuthzAminoConverters(): Record<string, AminoConverter> {
+  const aminoTypes = new AminoTypes({
+    ...createDefaultAminoConverters(),
+  })
+
+  return {
+    [MessageTypeUrls.Exec]: {
+      aminoType: 'cosmos-sdk/MsgExec',
+      toAmino: ({ msgs, grantee }: MsgExec) => ({
+        msgs: msgs.map(msg => aminoTypes.toAmino(msg)),
+        grantee,
+      }),
+      /* eslint-disable camelcase */
+      fromAmino: ({
+        msgs,
+        grantee,
+      }: {
+        grantee: string
+        msgs: AminoMsg[]
+      }): MsgExec =>
+        MsgExec.fromPartial({
+          msgs: msgs.map(msg => aminoTypes.fromAmino(msg)),
+          grantee,
+        }),
+    },
+  }
+}
diff --git a/packages/client/src/helpers/broadcast-maker.ts b/packages/client/src/helpers/broadcast-maker.ts
index b11e7c03..eabdfe6d 100644
--- a/packages/client/src/helpers/broadcast-maker.ts
+++ b/packages/client/src/helpers/broadcast-maker.ts
@@ -7,6 +7,8 @@ import {
 } from '@cosmjs/proto-signing/build/registry'
 import {
   type Account,
+  AminoTypes,
+  createDefaultAminoConverters,
   type DeliverTxResponse,
   GasPrice,
   SigningStargateClient,
@@ -15,6 +17,7 @@ import {
 import { BaseAccount } from '@/codec/cosmos/auth/auth'
 import { EthAccount } from '@/codec/ethermint/account'
 import { WalletBroadcastError } from '@/errors'
+import { createAuthzAminoConverters } from '@/helpers/authz'
 import type { Config, Wallet } from '@/types'
 
 import { stub } from './stub'
@@ -38,6 +41,10 @@ export const makeBroadcastMaker = async (config: Config, wallet: Wallet) => {
           }
           return baseAccountToAccount(EthAccount.decode(acc.value).baseAccount!)
         },
+        aminoTypes: new AminoTypes({
+          ...createDefaultAminoConverters(),
+          ...createAuthzAminoConverters(),
+        }),
       },
     )