diff --git a/packages/bcp/src/decode.ts b/packages/bcp/src/decode.ts
index 72eaf9cf..a6c40170 100644
--- a/packages/bcp/src/decode.ts
+++ b/packages/bcp/src/decode.ts
@@ -1,4 +1,4 @@
-import { TxsResponse } from "@cosmwasm/sdk";
+import { isAminoStdTx, TxsResponse } from "@cosmwasm/sdk";
 import {
   Address,
   Algorithm,
@@ -19,7 +19,7 @@ import {
 import { Encoding } from "@iov/encoding";
 import amino from "@tendermint/amino-js";
 
-import { coinToAmount, isAminoStdTx, TokenInfos } from "./types";
+import { coinToAmount, TokenInfos } from "./types";
 
 const { fromBase64 } = Encoding;
 
diff --git a/packages/bcp/src/types.ts b/packages/bcp/src/types.ts
index 8a77aa71..8e3bccc1 100644
--- a/packages/bcp/src/types.ts
+++ b/packages/bcp/src/types.ts
@@ -1,13 +1,6 @@
 import { Amount, Nonce, Token } from "@iov/bcp";
 import amino from "@tendermint/amino-js";
 
-export function isAminoStdTx(txValue: amino.TxValue): txValue is amino.StdTx {
-  const { memo, msg, fee, signatures } = txValue as amino.StdTx;
-  return (
-    typeof memo === "string" && Array.isArray(msg) && typeof fee === "object" && Array.isArray(signatures)
-  );
-}
-
 export interface TokenInfo extends Token {
   readonly denom: string;
 }
diff --git a/packages/sdk/src/index.ts b/packages/sdk/src/index.ts
index c5976e02..f8dbdc95 100644
--- a/packages/sdk/src/index.ts
+++ b/packages/sdk/src/index.ts
@@ -1,2 +1,2 @@
 export { RestClient, TxsResponse } from "./restclient";
-export { AminoTx } from "./types";
+export { AminoTx, isAminoStdTx } from "./types";
diff --git a/packages/sdk/src/types.ts b/packages/sdk/src/types.ts
index 7b5d6599..c8a0ef72 100644
--- a/packages/sdk/src/types.ts
+++ b/packages/sdk/src/types.ts
@@ -1,3 +1,10 @@
 import amino from "@tendermint/amino-js";
 
 export type AminoTx = amino.Tx & { readonly value: amino.StdTx };
+
+export function isAminoStdTx(txValue: amino.TxValue): txValue is amino.StdTx {
+  const { memo, msg, fee, signatures } = txValue as amino.StdTx;
+  return (
+    typeof memo === "string" && Array.isArray(msg) && typeof fee === "object" && Array.isArray(signatures)
+  );
+}
diff --git a/packages/sdk/types/index.d.ts b/packages/sdk/types/index.d.ts
index c5976e02..f8dbdc95 100644
--- a/packages/sdk/types/index.d.ts
+++ b/packages/sdk/types/index.d.ts
@@ -1,2 +1,2 @@
 export { RestClient, TxsResponse } from "./restclient";
-export { AminoTx } from "./types";
+export { AminoTx, isAminoStdTx } from "./types";
diff --git a/packages/sdk/types/types.d.ts b/packages/sdk/types/types.d.ts
index e0c11766..cb5a44a9 100644
--- a/packages/sdk/types/types.d.ts
+++ b/packages/sdk/types/types.d.ts
@@ -2,3 +2,4 @@ import amino from "@tendermint/amino-js";
 export declare type AminoTx = amino.Tx & {
   readonly value: amino.StdTx;
 };
+export declare function isAminoStdTx(txValue: amino.TxValue): txValue is amino.StdTx;