diff --git a/packages/proto-signing/src/index.ts b/packages/proto-signing/src/index.ts
index 2041cccd..8b2788e7 100644
--- a/packages/proto-signing/src/index.ts
+++ b/packages/proto-signing/src/index.ts
@@ -1,4 +1,4 @@
 export { Coin } from "./msgs";
 export { cosmosField } from "./decorator";
 export { Registry } from "./registry";
-export { makeSignBytes } from "./signing";
+export { makeAuthInfo, makeSignBytes } from "./signing";
diff --git a/packages/proto-signing/src/signing.spec.ts b/packages/proto-signing/src/signing.spec.ts
index 261ea5ee..36508e8d 100644
--- a/packages/proto-signing/src/signing.spec.ts
+++ b/packages/proto-signing/src/signing.spec.ts
@@ -1,12 +1,11 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { Bech32, fromBase64, fromHex, toHex } from "@cosmjs/encoding";
 import { Secp256k1Wallet } from "@cosmjs/launchpad";
-import Long from "long";
 
 import { cosmos } from "./codec";
 import { defaultRegistry } from "./msgs";
 import { Registry, TxBodyValue } from "./registry";
-import { makeSignBytes } from "./signing";
+import { makeAuthInfo, makeSignBytes } from "./signing";
 
 const { AuthInfo, Tx, TxBody } = cosmos.tx;
 const { PublicKey } = cosmos.crypto;
@@ -61,13 +60,13 @@ const testVectors = [
   },
 ];
 
-describe("signing demo", () => {
+describe("signing", () => {
   const chainId = "simd-testing";
   const toAddress = Uint8Array.from({ length: 20 }, (_, i) => i + 1);
 
   const sendAmount = "1234567";
   const sendDenom = "ucosm";
-  const gasLimit = Long.fromNumber(200000);
+  const gasLimit = 200000;
 
   it("correctly parses test vectors", async () => {
     const wallet = await Secp256k1Wallet.fromMnemonic(faucet.mnemonic);
@@ -130,22 +129,7 @@ describe("signing demo", () => {
     });
     const txBody = TxBody.decode(txBodyBytes);
 
-    const authInfo = {
-      signerInfos: [
-        {
-          publicKey: publicKey,
-          modeInfo: {
-            single: {
-              mode: cosmos.tx.signing.SignMode.SIGN_MODE_DIRECT,
-            },
-          },
-        },
-      ],
-      fee: {
-        gasLimit: gasLimit,
-      },
-    };
-    const authInfoBytes = Uint8Array.from(AuthInfo.encode(authInfo).finish());
+    const authInfoBytes = makeAuthInfo([publicKey], gasLimit);
     const accountNumber = 1;
 
     await Promise.all(
@@ -154,9 +138,10 @@ describe("signing demo", () => {
         expect(toHex(signDocBytes)).toEqual(signBytes);
 
         const signature = await wallet.sign(address, signDocBytes);
+        // TODO: Why is this not a TxRaw? https://github.com/CosmWasm/cosmjs/issues/383
         const txRaw = Tx.create({
           body: txBody,
-          authInfo: authInfo,
+          authInfo: AuthInfo.decode(authInfoBytes),
           signatures: [fromBase64(signature.signature)],
         });
         const txRawBytes = Uint8Array.from(Tx.encode(txRaw).finish());
diff --git a/packages/proto-signing/src/signing.ts b/packages/proto-signing/src/signing.ts
index 2b6be395..5bc6cc7c 100644
--- a/packages/proto-signing/src/signing.ts
+++ b/packages/proto-signing/src/signing.ts
@@ -1,8 +1,28 @@
 /* eslint-disable @typescript-eslint/naming-convention */
+import Long from "long";
+
 import { omitDefaults } from "./adr27";
 import { cosmos } from "./codec";
 
-const { SignDoc } = cosmos.tx;
+const { SignDoc, AuthInfo } = cosmos.tx;
+
+/**
+ * Creates and serializes an AuthInfo document using SIGN_MODE_DIRECT.
+ */
+export function makeAuthInfo(pubkeys: readonly cosmos.crypto.IPublicKey[], gasLimit: number): Uint8Array {
+  const authInfo = {
+    signerInfos: pubkeys.map(
+      (pubkey): cosmos.tx.ISignerInfo => ({
+        publicKey: pubkey,
+        modeInfo: {
+          single: { mode: cosmos.tx.signing.SignMode.SIGN_MODE_DIRECT },
+        },
+      }),
+    ),
+    fee: { gasLimit: Long.fromNumber(gasLimit) },
+  };
+  return Uint8Array.from(AuthInfo.encode(authInfo).finish());
+}
 
 export function makeSignBytes(
   txBody: Uint8Array,
diff --git a/packages/proto-signing/types/index.d.ts b/packages/proto-signing/types/index.d.ts
index 2041cccd..8b2788e7 100644
--- a/packages/proto-signing/types/index.d.ts
+++ b/packages/proto-signing/types/index.d.ts
@@ -1,4 +1,4 @@
 export { Coin } from "./msgs";
 export { cosmosField } from "./decorator";
 export { Registry } from "./registry";
-export { makeSignBytes } from "./signing";
+export { makeAuthInfo, makeSignBytes } from "./signing";
diff --git a/packages/proto-signing/types/signing.d.ts b/packages/proto-signing/types/signing.d.ts
index 674d9797..ebb669f4 100644
--- a/packages/proto-signing/types/signing.d.ts
+++ b/packages/proto-signing/types/signing.d.ts
@@ -1,3 +1,11 @@
+import { cosmos } from "./codec";
+/**
+ * Creates and serializes an AuthInfo document using SIGN_MODE_DIRECT.
+ */
+export declare function makeAuthInfo(
+  pubkeys: readonly cosmos.crypto.IPublicKey[],
+  gasLimit: number,
+): Uint8Array;
 export declare function makeSignBytes(
   txBody: Uint8Array,
   authInfo: Uint8Array,
diff --git a/packages/stargate/src/stargateclient.searchtx.spec.ts b/packages/stargate/src/stargateclient.searchtx.spec.ts
index 791be4a2..be7c2893 100644
--- a/packages/stargate/src/stargateclient.searchtx.spec.ts
+++ b/packages/stargate/src/stargateclient.searchtx.spec.ts
@@ -1,9 +1,8 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { Bech32, fromBase64 } from "@cosmjs/encoding";
 import { Coin, coins, Secp256k1Wallet } from "@cosmjs/launchpad";
-import { makeSignBytes, Registry } from "@cosmjs/proto-signing";
+import { makeAuthInfo, makeSignBytes, Registry } from "@cosmjs/proto-signing";
 import { assert, sleep } from "@cosmjs/utils";
-import Long from "long";
 
 import { cosmos } from "./codec";
 import {
@@ -56,31 +55,16 @@ async function sendTokens(
   };
   const txBodyBytes = registry.encode(txBodyFields);
   const txBody = TxBody.decode(txBodyBytes);
-
-  const authInfo = {
-    signerInfos: [
-      {
-        publicKey: publicKey,
-        modeInfo: {
-          single: {
-            mode: cosmos.tx.signing.SignMode.SIGN_MODE_DIRECT,
-          },
-        },
-      },
-    ],
-    fee: {
-      gasLimit: Long.fromNumber(200000),
-    },
-  };
-  const authInfoBytes = Uint8Array.from(AuthInfo.encode(authInfo).finish());
+  const authInfoBytes = makeAuthInfo([publicKey], 200000);
 
   const { accountNumber, sequence } = (await client.getSequence(walletAddress))!;
   const chainId = await client.getChainId();
   const signDocBytes = makeSignBytes(txBodyBytes, authInfoBytes, chainId, accountNumber, sequence);
   const signature = await wallet.sign(walletAddress, signDocBytes);
+  // TODO: Why is this not a TxRaw? https://github.com/CosmWasm/cosmjs/issues/383
   const txRaw = Tx.create({
     body: txBody,
-    authInfo: authInfo,
+    authInfo: AuthInfo.decode(authInfoBytes),
     signatures: [fromBase64(signature.signature)],
   });
   const txRawBytes = Uint8Array.from(Tx.encode(txRaw).finish());
diff --git a/packages/stargate/src/stargateclient.spec.ts b/packages/stargate/src/stargateclient.spec.ts
index a08ce8b0..c8682f4f 100644
--- a/packages/stargate/src/stargateclient.spec.ts
+++ b/packages/stargate/src/stargateclient.spec.ts
@@ -1,9 +1,8 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { Bech32, fromBase64 } from "@cosmjs/encoding";
 import { Secp256k1Wallet } from "@cosmjs/launchpad";
-import { makeSignBytes, Registry } from "@cosmjs/proto-signing";
+import { makeAuthInfo, makeSignBytes, Registry } from "@cosmjs/proto-signing";
 import { assert, sleep } from "@cosmjs/utils";
-import Long from "long";
 import { ReadonlyDate } from "readonly-date";
 
 import { cosmos } from "./codec";
@@ -279,30 +278,16 @@ describe("StargateClient", () => {
       };
       const txBodyBytes = registry.encode(txBodyFields);
       const txBody = TxBody.decode(txBodyBytes);
-      const authInfo = {
-        signerInfos: [
-          {
-            publicKey: publicKey,
-            modeInfo: {
-              single: {
-                mode: cosmos.tx.signing.SignMode.SIGN_MODE_DIRECT,
-              },
-            },
-          },
-        ],
-        fee: {
-          gasLimit: Long.fromNumber(200000),
-        },
-      };
-      const authInfoBytes = Uint8Array.from(AuthInfo.encode(authInfo).finish());
+      const authInfoBytes = makeAuthInfo([publicKey], 200000);
 
       const chainId = await client.getChainId();
       const { accountNumber, sequence } = (await client.getSequence(address))!;
       const signDocBytes = makeSignBytes(txBodyBytes, authInfoBytes, chainId, accountNumber, sequence);
       const signature = await wallet.sign(address, signDocBytes);
+      // TODO: Why is this not a TxRaw? https://github.com/CosmWasm/cosmjs/issues/383
       const txRaw = Tx.create({
         body: txBody,
-        authInfo: authInfo,
+        authInfo: AuthInfo.decode(authInfoBytes),
         signatures: [fromBase64(signature.signature)],
       });
       const txRawBytes = Uint8Array.from(Tx.encode(txRaw).finish());