diff --git a/packages/bcp/src/encode.ts b/packages/bcp/src/encode.ts
index ca606156..23f7385d 100644
--- a/packages/bcp/src/encode.ts
+++ b/packages/bcp/src/encode.ts
@@ -10,6 +10,7 @@ import {
   SignedTransaction,
   UnsignedTransaction,
 } from "@iov/bcp";
+import { Secp256k1 } from "@iov/crypto";
 import { Encoding } from "@iov/encoding";
 
 import { BankTokens, Erc20Token } from "./types";
@@ -70,8 +71,10 @@ export function encodeFee(fee: Fee, tokens: BankTokens): types.StdFee {
 
 export function encodeFullSignature(fullSignature: FullSignature): types.StdSignature {
   switch (fullSignature.pubkey.algo) {
-    case Algorithm.Secp256k1:
-      return encodeSecp256k1Signature(fullSignature.pubkey.data, fullSignature.signature);
+    case Algorithm.Secp256k1: {
+      const normalizedSignature = Secp256k1.trimRecoveryByte(fullSignature.signature);
+      return encodeSecp256k1Signature(fullSignature.pubkey.data, normalizedSignature);
+    }
     default:
       throw new Error("Unsupported signing algorithm");
   }
diff --git a/packages/sdk/src/signature.spec.ts b/packages/sdk/src/signature.spec.ts
index 23dc8cda..b95612d1 100644
--- a/packages/sdk/src/signature.spec.ts
+++ b/packages/sdk/src/signature.spec.ts
@@ -39,7 +39,7 @@ describe("signature", () => {
       });
     });
 
-    it("removes recovery values from signature data", () => {
+    it("throws if signature contains recovery byte", () => {
       const pubkey = fromBase64("AtQaCqFnshaZQp6rIkvAPyzThvCvXSDO+9AzbxVErqJP");
       const signature = Uint8Array.from([
         ...fromBase64(
@@ -47,14 +47,9 @@ describe("signature", () => {
         ),
         99,
       ]);
-      expect(encodeSecp256k1Signature(pubkey, signature)).toEqual({
-        // eslint-disable-next-line @typescript-eslint/camelcase
-        pub_key: {
-          type: "tendermint/PubKeySecp256k1",
-          value: "AtQaCqFnshaZQp6rIkvAPyzThvCvXSDO+9AzbxVErqJP",
-        },
-        signature: "1nUcIH0CLT0/nQ0mBTDrT6kMG20NY/PsH7P2gc4bpYNGLEYjBmdWevXUJouSE/9A/60QG9cYeqyTe5kFDeIPxQ==",
-      });
+      expect(() => encodeSecp256k1Signature(pubkey, signature)).toThrowError(
+        /signature must be 64 bytes long/i,
+      );
     });
   });
 
diff --git a/packages/sdk/src/signature.ts b/packages/sdk/src/signature.ts
index 56eb6af6..a71f03eb 100644
--- a/packages/sdk/src/signature.ts
+++ b/packages/sdk/src/signature.ts
@@ -1,15 +1,25 @@
-import { Secp256k1 } from "@iov/crypto";
 import { Encoding } from "@iov/encoding";
 
 import { encodeSecp256k1Pubkey } from "./pubkey";
 import { pubkeyType, StdSignature } from "./types";
 
+/**
+ * Takes a binary pubkey and signature to create a signature object
+ *
+ * @param pubkey a secp256k1 public key
+ * @param signature a 64 byte fixed length representation of secp256k1 signature components r and s
+ */
 export function encodeSecp256k1Signature(pubkey: Uint8Array, signature: Uint8Array): StdSignature {
+  if (signature.length !== 64) {
+    throw new Error(
+      "Signature must be 64 bytes long. Cosmos SDK uses a 2x32 byte fixed length encoding for the secp256k1 signature integers r and s.",
+    );
+  }
+
   return {
     // eslint-disable-next-line @typescript-eslint/camelcase
     pub_key: encodeSecp256k1Pubkey(pubkey),
-    // Recovery seems to be unused
-    signature: Encoding.toBase64(Secp256k1.trimRecoveryByte(signature)),
+    signature: Encoding.toBase64(signature),
   };
 }
 
diff --git a/packages/sdk/types/signature.d.ts b/packages/sdk/types/signature.d.ts
index c6908ddc..a2c9586c 100644
--- a/packages/sdk/types/signature.d.ts
+++ b/packages/sdk/types/signature.d.ts
@@ -1,4 +1,10 @@
 import { StdSignature } from "./types";
+/**
+ * Takes a binary pubkey and signature to create a signature object
+ *
+ * @param pubkey a secp256k1 public key
+ * @param signature a 64 byte fixed length representation of secp256k1 signature components r and s
+ */
 export declare function encodeSecp256k1Signature(pubkey: Uint8Array, signature: Uint8Array): StdSignature;
 export declare function decodeSignature(
   signature: StdSignature,