diff --git a/packages/sdk/src/types.ts b/packages/sdk/src/types.ts
index 5c3f1d60..2e1ecbe8 100644
--- a/packages/sdk/src/types.ts
+++ b/packages/sdk/src/types.ts
@@ -110,7 +110,7 @@ export interface PubKey {
   readonly value: string;
 }
 
-export const pubkeyTypes: string[] = [
+export const pubkeyTypes: readonly string[] = [
   "tendermint/PubKeySecp256k1",
   "tendermint/PubKeyEd25519",
   "tendermint/PubKeySr25519",
diff --git a/packages/sdk/types/types.d.ts b/packages/sdk/types/types.d.ts
index 81880b03..fc750bf8 100644
--- a/packages/sdk/types/types.d.ts
+++ b/packages/sdk/types/types.d.ts
@@ -74,7 +74,7 @@ export interface PubKey {
   readonly type: string;
   readonly value: string;
 }
-export declare const pubkeyTypes: string[];
+export declare const pubkeyTypes: readonly string[];
 export declare type Bech32PubKey = string;
 export interface BaseAccount {
   /** Bech32 account address */