diff --git a/CHANGELOG.md b/CHANGELOG.md
index c5d0b2f8..4b76adeb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,7 +35,10 @@ and this project adheres to
 - @cosmjs/stargate: Add `granteeGrants` and `granterGrants` queries to
   `AuthzExtension` ([#1308]).
 - @cosmjs/tendermint-rpc: Add new `Tendermint37Client` and remove unused
-  `Tendermint35Client` ([#1376]).
+  `Tendermint35Client`; Add `TendermintClient` as a union type for
+  `Tendermint34Client` or `Tendermint37Client` and
+  `isTendermint34Client`/`isTendermint37Client` to get the specific type
+  ([#1376]).
 
 [#1308]: https://github.com/cosmos/cosmjs/pull/1308
 [#1376]: https://github.com/cosmos/cosmjs/pull/1376
diff --git a/packages/cosmwasm-stargate/src/cosmwasmclient.ts b/packages/cosmwasm-stargate/src/cosmwasmclient.ts
index 158d3eab..866daf4f 100644
--- a/packages/cosmwasm-stargate/src/cosmwasmclient.ts
+++ b/packages/cosmwasm-stargate/src/cosmwasmclient.ts
@@ -25,7 +25,12 @@ import {
   TimeoutError,
   TxExtension,
 } from "@cosmjs/stargate";
-import { HttpEndpoint, Tendermint34Client, toRfc3339WithNanoseconds } from "@cosmjs/tendermint-rpc";
+import {
+  HttpEndpoint,
+  Tendermint34Client,
+  TendermintClient,
+  toRfc3339WithNanoseconds,
+} from "@cosmjs/tendermint-rpc";
 import { assert, sleep } from "@cosmjs/utils";
 import {
   CodeInfoResponse,
@@ -77,14 +82,14 @@ export interface ContractCodeHistoryEntry {
 
 /** Use for testing only */
 export interface PrivateCosmWasmClient {
-  readonly tmClient: Tendermint34Client | undefined;
+  readonly tmClient: TendermintClient | undefined;
   readonly queryClient:
     | (QueryClient & AuthExtension & BankExtension & TxExtension & WasmExtension)
     | undefined;
 }
 
 export class CosmWasmClient {
-  private readonly tmClient: Tendermint34Client | undefined;
+  private readonly tmClient: TendermintClient | undefined;
   private readonly queryClient:
     | (QueryClient & AuthExtension & BankExtension & TxExtension & WasmExtension)
     | undefined;
@@ -96,7 +101,7 @@ export class CosmWasmClient {
     return new CosmWasmClient(tmClient);
   }
 
-  protected constructor(tmClient: Tendermint34Client | undefined) {
+  protected constructor(tmClient: TendermintClient | undefined) {
     if (tmClient) {
       this.tmClient = tmClient;
       this.queryClient = QueryClient.withExtensions(
@@ -109,11 +114,11 @@ export class CosmWasmClient {
     }
   }
 
-  protected getTmClient(): Tendermint34Client | undefined {
+  protected getTmClient(): TendermintClient | undefined {
     return this.tmClient;
   }
 
-  protected forceGetTmClient(): Tendermint34Client {
+  protected forceGetTmClient(): TendermintClient {
     if (!this.tmClient) {
       throw new Error(
         "Tendermint client not available. You cannot use online functionality in offline mode.",
diff --git a/packages/cosmwasm-stargate/src/signingcosmwasmclient.ts b/packages/cosmwasm-stargate/src/signingcosmwasmclient.ts
index 5d03812a..e3843404 100644
--- a/packages/cosmwasm-stargate/src/signingcosmwasmclient.ts
+++ b/packages/cosmwasm-stargate/src/signingcosmwasmclient.ts
@@ -31,7 +31,7 @@ import {
   SignerData,
   StdFee,
 } from "@cosmjs/stargate";
-import { HttpEndpoint, Tendermint34Client } from "@cosmjs/tendermint-rpc";
+import { HttpEndpoint, Tendermint34Client, TendermintClient } from "@cosmjs/tendermint-rpc";
 import { assert, assertDefined } from "@cosmjs/utils";
 import { MsgWithdrawDelegatorReward } from "cosmjs-types/cosmos/distribution/v1beta1/tx";
 import { MsgDelegate, MsgUndelegate } from "cosmjs-types/cosmos/staking/v1beta1/tx";
@@ -209,7 +209,7 @@ export class SigningCosmWasmClient extends CosmWasmClient {
   }
 
   protected constructor(
-    tmClient: Tendermint34Client | undefined,
+    tmClient: TendermintClient | undefined,
     signer: OfflineSigner,
     options: SigningCosmWasmClientOptions,
   ) {
diff --git a/packages/stargate/src/queryclient/queryclient.ts b/packages/stargate/src/queryclient/queryclient.ts
index 66644433..aaa000a9 100644
--- a/packages/stargate/src/queryclient/queryclient.ts
+++ b/packages/stargate/src/queryclient/queryclient.ts
@@ -2,7 +2,7 @@
 import { iavlSpec, ics23, tendermintSpec, verifyExistence, verifyNonExistence } from "@confio/ics23";
 import { toAscii, toHex } from "@cosmjs/encoding";
 import { firstEvent } from "@cosmjs/stream";
-import { tendermint34, Tendermint34Client } from "@cosmjs/tendermint-rpc";
+import { tendermint34, TendermintClient } from "@cosmjs/tendermint-rpc";
 import { arrayContentEquals, assert, assertDefined, isNonNullObject, sleep } from "@cosmjs/utils";
 import { ProofOps } from "cosmjs-types/tendermint/crypto/proof";
 import { Stream } from "xstream";
@@ -45,24 +45,24 @@ export interface QueryAbciResponse {
 
 export class QueryClient {
   /** Constructs a QueryClient with 0 extensions */
-  public static withExtensions(tmClient: Tendermint34Client): QueryClient;
+  public static withExtensions(tmClient: TendermintClient): QueryClient;
 
   /** Constructs a QueryClient with 1 extension */
   public static withExtensions<A extends object>(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
   ): QueryClient & A;
 
   /** Constructs a QueryClient with 2 extensions */
   public static withExtensions<A extends object, B extends object>(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
   ): QueryClient & A & B;
 
   /** Constructs a QueryClient with 3 extensions */
   public static withExtensions<A extends object, B extends object, C extends object>(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -70,7 +70,7 @@ export class QueryClient {
 
   /** Constructs a QueryClient with 4 extensions */
   public static withExtensions<A extends object, B extends object, C extends object, D extends object>(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -85,7 +85,7 @@ export class QueryClient {
     D extends object,
     E extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -102,7 +102,7 @@ export class QueryClient {
     E extends object,
     F extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -121,7 +121,7 @@ export class QueryClient {
     F extends object,
     G extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -142,7 +142,7 @@ export class QueryClient {
     G extends object,
     H extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -165,7 +165,7 @@ export class QueryClient {
     H extends object,
     I extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -190,7 +190,7 @@ export class QueryClient {
     I extends object,
     J extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -217,7 +217,7 @@ export class QueryClient {
     J extends object,
     K extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -246,7 +246,7 @@ export class QueryClient {
     K extends object,
     L extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -277,7 +277,7 @@ export class QueryClient {
     L extends object,
     M extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -310,7 +310,7 @@ export class QueryClient {
     M extends object,
     N extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -345,7 +345,7 @@ export class QueryClient {
     N extends object,
     O extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -382,7 +382,7 @@ export class QueryClient {
     O extends object,
     P extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -421,7 +421,7 @@ export class QueryClient {
     P extends object,
     Q extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -462,7 +462,7 @@ export class QueryClient {
     Q extends object,
     R extends object,
   >(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     setupExtensionA: QueryExtensionSetup<A>,
     setupExtensionB: QueryExtensionSetup<B>,
     setupExtensionC: QueryExtensionSetup<C>,
@@ -484,7 +484,7 @@ export class QueryClient {
   ): QueryClient & A & B & C & D & E & F & G & H & I & J & K & L & M & N & O & P & Q & R;
 
   public static withExtensions(
-    tmClient: Tendermint34Client,
+    tmClient: TendermintClient,
     ...extensionSetups: Array<QueryExtensionSetup<object>>
   ): any {
     const client = new QueryClient(tmClient);
@@ -506,9 +506,9 @@ export class QueryClient {
     return client;
   }
 
-  private readonly tmClient: Tendermint34Client;
+  private readonly tmClient: TendermintClient;
 
-  public constructor(tmClient: Tendermint34Client) {
+  public constructor(tmClient: TendermintClient) {
     this.tmClient = tmClient;
   }
 
diff --git a/packages/stargate/src/signingstargateclient.ts b/packages/stargate/src/signingstargateclient.ts
index ed89c7e9..73fa8143 100644
--- a/packages/stargate/src/signingstargateclient.ts
+++ b/packages/stargate/src/signingstargateclient.ts
@@ -12,7 +12,7 @@ import {
   Registry,
   TxBodyEncodeObject,
 } from "@cosmjs/proto-signing";
-import { HttpEndpoint, Tendermint34Client } from "@cosmjs/tendermint-rpc";
+import { HttpEndpoint, Tendermint34Client, TendermintClient } from "@cosmjs/tendermint-rpc";
 import { assert, assertDefined } from "@cosmjs/utils";
 import { Coin } from "cosmjs-types/cosmos/base/v1beta1/coin";
 import { MsgWithdrawDelegatorReward } from "cosmjs-types/cosmos/distribution/v1beta1/tx";
@@ -140,7 +140,7 @@ export class SigningStargateClient extends StargateClient {
   }
 
   protected constructor(
-    tmClient: Tendermint34Client | undefined,
+    tmClient: TendermintClient | undefined,
     signer: OfflineSigner,
     options: SigningStargateClientOptions,
   ) {
diff --git a/packages/stargate/src/stargateclient.ts b/packages/stargate/src/stargateclient.ts
index 400f59ff..ddcf763a 100644
--- a/packages/stargate/src/stargateclient.ts
+++ b/packages/stargate/src/stargateclient.ts
@@ -2,7 +2,12 @@
 import { addCoins } from "@cosmjs/amino";
 import { toHex } from "@cosmjs/encoding";
 import { Uint53 } from "@cosmjs/math";
-import { HttpEndpoint, Tendermint34Client, toRfc3339WithNanoseconds } from "@cosmjs/tendermint-rpc";
+import {
+  HttpEndpoint,
+  Tendermint34Client,
+  TendermintClient,
+  toRfc3339WithNanoseconds,
+} from "@cosmjs/tendermint-rpc";
 import { assert, sleep } from "@cosmjs/utils";
 import { MsgData } from "cosmjs-types/cosmos/base/abci/v1beta1/abci";
 import { Coin } from "cosmjs-types/cosmos/base/v1beta1/coin";
@@ -171,7 +176,7 @@ export class BroadcastTxError extends Error {
 
 /** Use for testing only */
 export interface PrivateStargateClient {
-  readonly tmClient: Tendermint34Client | undefined;
+  readonly tmClient: TendermintClient | undefined;
 }
 
 export interface StargateClientOptions {
@@ -179,7 +184,7 @@ export interface StargateClientOptions {
 }
 
 export class StargateClient {
-  private readonly tmClient: Tendermint34Client | undefined;
+  private readonly tmClient: TendermintClient | undefined;
   private readonly queryClient:
     | (QueryClient & AuthExtension & BankExtension & StakingExtension & TxExtension)
     | undefined;
@@ -194,7 +199,7 @@ export class StargateClient {
     return new StargateClient(tmClient, options);
   }
 
-  protected constructor(tmClient: Tendermint34Client | undefined, options: StargateClientOptions) {
+  protected constructor(tmClient: TendermintClient | undefined, options: StargateClientOptions) {
     if (tmClient) {
       this.tmClient = tmClient;
       this.queryClient = QueryClient.withExtensions(
@@ -209,11 +214,11 @@ export class StargateClient {
     this.accountParser = accountParser;
   }
 
-  protected getTmClient(): Tendermint34Client | undefined {
+  protected getTmClient(): TendermintClient | undefined {
     return this.tmClient;
   }
 
-  protected forceGetTmClient(): Tendermint34Client {
+  protected forceGetTmClient(): TendermintClient {
     if (!this.tmClient) {
       throw new Error(
         "Tendermint client not available. You cannot use online functionality in offline mode.",
diff --git a/packages/tendermint-rpc/src/index.ts b/packages/tendermint-rpc/src/index.ts
index 757012a3..5b645eff 100644
--- a/packages/tendermint-rpc/src/index.ts
+++ b/packages/tendermint-rpc/src/index.ts
@@ -97,6 +97,7 @@ export * as tendermint34 from "./tendermint34";
 export { Tendermint34Client } from "./tendermint34";
 export * as tendermint37 from "./tendermint37";
 export { Tendermint37Client } from "./tendermint37";
+export { isTendermint34Client, isTendermint37Client, TendermintClient } from "./tendermintclient";
 export {
   BlockIdFlag,
   CommitSignature,
diff --git a/packages/tendermint-rpc/src/tendermintclient.ts b/packages/tendermint-rpc/src/tendermintclient.ts
new file mode 100644
index 00000000..3d07558b
--- /dev/null
+++ b/packages/tendermint-rpc/src/tendermintclient.ts
@@ -0,0 +1,13 @@
+import { Tendermint34Client } from "./tendermint34";
+import { Tendermint37Client } from "./tendermint37";
+
+/** A TendermintClient is either a Tendermint34Client or a Tendermint37Client */
+export type TendermintClient = Tendermint34Client | Tendermint37Client;
+
+export function isTendermint34Client(client: TendermintClient): client is Tendermint34Client {
+  return client instanceof Tendermint34Client;
+}
+
+export function isTendermint37Client(client: TendermintClient): client is Tendermint37Client {
+  return client instanceof Tendermint37Client;
+}