diff --git a/.eslintrc.js b/.eslintrc.js
index ae6c05b0..d78f9590 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -27,10 +27,11 @@ module.exports = {
     "no-shadow": "warn",
     "no-unused-vars": "off", // disabled in favour of @typescript-eslint/no-unused-vars, see https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/no-unused-vars.md
     "prefer-const": "warn",
-    "radix": ["warn", "always"],
+    radix: ["warn", "always"],
     "spaced-comment": ["warn", "always", { line: { markers: ["/ <reference"] } }],
     "import/no-cycle": "warn",
     "simple-import-sort/sort": "warn",
+    "@typescript-eslint/array-type": ["warn", { default: "array-simple" }],
     "@typescript-eslint/await-thenable": "warn",
     "@typescript-eslint/explicit-function-return-type": ["warn", { allowExpressions: true }],
     "@typescript-eslint/no-dynamic-delete": "warn",
diff --git a/packages/cosmwasm/src/cosmwasmclient.ts b/packages/cosmwasm/src/cosmwasmclient.ts
index c126bf66..4d7d4a4c 100644
--- a/packages/cosmwasm/src/cosmwasmclient.ts
+++ b/packages/cosmwasm/src/cosmwasmclient.ts
@@ -23,7 +23,7 @@ export interface GetNonceResult {
 export interface Account {
   /** Bech32 account address */
   readonly address: string;
-  readonly balance: ReadonlyArray<Coin>;
+  readonly balance: readonly Coin[];
   readonly pubkey: PubKey | undefined;
   readonly accountNumber: number;
   readonly sequence: number;
@@ -68,7 +68,7 @@ export interface SearchBySentFromOrToQuery {
  * more powerful and slightly lower level than the other search options.
  */
 export interface SearchByTagsQuery {
-  readonly tags: readonly { readonly key: string; readonly value: string }[];
+  readonly tags: ReadonlyArray<{ readonly key: string; readonly value: string }>;
 }
 
 export type SearchTxQuery =
@@ -144,7 +144,7 @@ export interface Block {
   readonly id: string;
   readonly header: BlockHeader;
   /** Array of raw transactions */
-  readonly txs: ReadonlyArray<Uint8Array>;
+  readonly txs: readonly Uint8Array[];
 }
 
 /** Use for testing only */
diff --git a/packages/cosmwasm/src/msgs.ts b/packages/cosmwasm/src/msgs.ts
index d71a477d..7aae1b6c 100644
--- a/packages/cosmwasm/src/msgs.ts
+++ b/packages/cosmwasm/src/msgs.ts
@@ -41,7 +41,7 @@ export interface MsgInstantiateContract extends Msg {
     readonly label: string;
     /** Init message as JavaScript object */
     readonly init_msg: any;
-    readonly init_funds: ReadonlyArray<Coin>;
+    readonly init_funds: readonly Coin[];
     /** Bech32-encoded admin address */
     readonly admin?: string;
   };
@@ -106,7 +106,7 @@ export interface MsgExecuteContract extends Msg {
     readonly contract: string;
     /** Handle message as JavaScript object */
     readonly msg: any;
-    readonly sent_funds: ReadonlyArray<Coin>;
+    readonly sent_funds: readonly Coin[];
   };
 }
 
diff --git a/packages/cosmwasm/src/restclient.ts b/packages/cosmwasm/src/restclient.ts
index e1793716..a915f565 100644
--- a/packages/cosmwasm/src/restclient.ts
+++ b/packages/cosmwasm/src/restclient.ts
@@ -55,9 +55,9 @@ interface SmartQueryResponse {
 }
 
 /** Unfortunately, Cosmos SDK encodes empty arrays as null */
-type CosmosSdkArray<T> = ReadonlyArray<T> | null;
+type CosmosSdkArray<T> = readonly T[] | null;
 
-function normalizeArray<T>(backend: CosmosSdkArray<T>): ReadonlyArray<T> {
+function normalizeArray<T>(backend: CosmosSdkArray<T>): readonly T[] {
   return backend || [];
 }
 
diff --git a/packages/cosmwasm/types/cosmwasmclient.d.ts b/packages/cosmwasm/types/cosmwasmclient.d.ts
index 5e85137a..87e5360c 100644
--- a/packages/cosmwasm/types/cosmwasmclient.d.ts
+++ b/packages/cosmwasm/types/cosmwasmclient.d.ts
@@ -9,7 +9,7 @@ export interface GetNonceResult {
 export interface Account {
   /** Bech32 account address */
   readonly address: string;
-  readonly balance: ReadonlyArray<Coin>;
+  readonly balance: readonly Coin[];
   readonly pubkey: PubKey | undefined;
   readonly accountNumber: number;
   readonly sequence: number;
@@ -44,10 +44,10 @@ export interface SearchBySentFromOrToQuery {
  * more powerful and slightly lower level than the other search options.
  */
 export interface SearchByTagsQuery {
-  readonly tags: readonly {
+  readonly tags: ReadonlyArray<{
     readonly key: string;
     readonly value: string;
-  }[];
+  }>;
 }
 export declare type SearchTxQuery =
   | SearchByIdQuery
@@ -99,7 +99,7 @@ export interface Block {
   readonly id: string;
   readonly header: BlockHeader;
   /** Array of raw transactions */
-  readonly txs: ReadonlyArray<Uint8Array>;
+  readonly txs: readonly Uint8Array[];
 }
 /** Use for testing only */
 export interface PrivateCosmWasmClient {
diff --git a/packages/cosmwasm/types/msgs.d.ts b/packages/cosmwasm/types/msgs.d.ts
index c070fa18..5250100b 100644
--- a/packages/cosmwasm/types/msgs.d.ts
+++ b/packages/cosmwasm/types/msgs.d.ts
@@ -36,7 +36,7 @@ export interface MsgInstantiateContract extends Msg {
     readonly label: string;
     /** Init message as JavaScript object */
     readonly init_msg: any;
-    readonly init_funds: ReadonlyArray<Coin>;
+    readonly init_funds: readonly Coin[];
     /** Bech32-encoded admin address */
     readonly admin?: string;
   };
@@ -89,7 +89,7 @@ export interface MsgExecuteContract extends Msg {
     readonly contract: string;
     /** Handle message as JavaScript object */
     readonly msg: any;
-    readonly sent_funds: ReadonlyArray<Coin>;
+    readonly sent_funds: readonly Coin[];
   };
 }
 export declare function isMsgExecuteContract(msg: Msg): msg is MsgExecuteContract;
diff --git a/packages/crypto/src/secp256k1.spec.ts b/packages/crypto/src/secp256k1.spec.ts
index 36833fdf..84586cb8 100644
--- a/packages/crypto/src/secp256k1.spec.ts
+++ b/packages/crypto/src/secp256k1.spec.ts
@@ -194,11 +194,11 @@ describe("Secp256k1", () => {
 
   it("verifies unnormalized pyca/cryptography signatures", async () => {
     // signatures are mixed lowS and non-lowS, prehash type is sha256
-    const data: readonly {
+    const data: ReadonlyArray<{
       readonly message: Uint8Array;
       readonly privkey: Uint8Array;
       readonly signature: Uint8Array;
-    }[] = [
+    }> = [
       {
         message: fromHex(
           "5c868fedb8026979ebd26f1ba07c27eedf4ff6d10443505a96ecaf21ba8c4f0937b3cd23ffdc3dd429d4cd1905fb8dbcceeff1350020e18b58d2ba70887baa3a9b783ad30d3fbf210331cdd7df8d77defa398cdacdfc2e359c7ba4cae46bb74401deb417f8b912a1aa966aeeba9c39c7dd22479ae2b30719dca2f2206c5eb4b7",
@@ -395,11 +395,11 @@ describe("Secp256k1", () => {
 
   it("matches normalized pyca/cryptography signatures", async () => {
     // signatures are normalized to lowS, prehash type is sha256
-    const data: readonly {
+    const data: ReadonlyArray<{
       readonly message: Uint8Array;
       readonly privkey: Uint8Array;
       readonly signature: Uint8Array;
-    }[] = [
+    }> = [
       {
         message: fromHex(
           "5c868fedb8026979ebd26f1ba07c27eedf4ff6d10443505a96ecaf21ba8c4f0937b3cd23ffdc3dd429d4cd1905fb8dbcceeff1350020e18b58d2ba70887baa3a9b783ad30d3fbf210331cdd7df8d77defa398cdacdfc2e359c7ba4cae46bb74401deb417f8b912a1aa966aeeba9c39c7dd22479ae2b30719dca2f2206c5eb4b7",
diff --git a/packages/faucet/src/actions/generate.ts b/packages/faucet/src/actions/generate.ts
index 096b18f7..73ed15c1 100644
--- a/packages/faucet/src/actions/generate.ts
+++ b/packages/faucet/src/actions/generate.ts
@@ -3,7 +3,7 @@ import { Bip39, Random } from "@cosmjs/crypto";
 import * as constants from "../constants";
 import { createPens } from "../profile";
 
-export async function generate(args: ReadonlyArray<string>): Promise<void> {
+export async function generate(args: readonly string[]): Promise<void> {
   if (args.length < 1) {
     throw Error(
       `Not enough arguments for action 'generate'. See '${constants.binaryName} help' or README for arguments.`,
diff --git a/packages/faucet/src/actions/start/start.ts b/packages/faucet/src/actions/start/start.ts
index ad1c29ed..9c72cd01 100644
--- a/packages/faucet/src/actions/start/start.ts
+++ b/packages/faucet/src/actions/start/start.ts
@@ -5,7 +5,7 @@ import * as constants from "../../constants";
 import { logAccountsState } from "../../debugging";
 import { Faucet } from "../../faucet";
 
-export async function start(args: ReadonlyArray<string>): Promise<void> {
+export async function start(args: readonly string[]): Promise<void> {
   if (args.length < 1) {
     throw Error(
       `Not enough arguments for action 'start'. See '${constants.binaryName} help' or README for arguments.`,
diff --git a/packages/faucet/src/cli.ts b/packages/faucet/src/cli.ts
index ce90446e..a8d108cd 100644
--- a/packages/faucet/src/cli.ts
+++ b/packages/faucet/src/cli.ts
@@ -1,6 +1,6 @@
 import { generate, help, start, version } from "./actions";
 
-export function main(args: ReadonlyArray<string>): void {
+export function main(args: readonly string[]): void {
   if (args.length < 1) {
     help();
     process.exit(1);
diff --git a/packages/faucet/src/debugging.ts b/packages/faucet/src/debugging.ts
index 1db74139..ca7ba833 100644
--- a/packages/faucet/src/debugging.ts
+++ b/packages/faucet/src/debugging.ts
@@ -21,7 +21,7 @@ export function debugAccount(account: MinimalAccount, tokens: TokenConfiguration
   return `${account.address}: ${debugBalance(account.balance, tokens)}`;
 }
 
-export function logAccountsState(accounts: ReadonlyArray<MinimalAccount>, tokens: TokenConfiguration): void {
+export function logAccountsState(accounts: readonly MinimalAccount[], tokens: TokenConfiguration): void {
   if (accounts.length < 2) {
     throw new Error("List of accounts must contain at least one token holder and one distributor");
   }
diff --git a/packages/faucet/src/faucet.ts b/packages/faucet/src/faucet.ts
index 6e9f78fd..b6450956 100644
--- a/packages/faucet/src/faucet.ts
+++ b/packages/faucet/src/faucet.ts
@@ -38,7 +38,7 @@ export class Faucet {
     apiUrl: string,
     addressPrefix: string,
     config: TokenConfiguration,
-    pens: readonly [string, Pen][],
+    pens: ReadonlyArray<readonly [string, Pen]>,
     logging = false,
   ) {
     this.addressPrefix = addressPrefix;
@@ -64,7 +64,7 @@ export class Faucet {
   /**
    * Returns a list of ticker symbols of tokens owned by the the holder and configured in the faucet
    */
-  public async availableTokens(): Promise<ReadonlyArray<string>> {
+  public async availableTokens(): Promise<readonly string[]> {
     const holderAccount = await this.readOnlyClient.getAccount(this.holderAddress);
     const balance = holderAccount ? holderAccount.balance : [];
 
@@ -99,7 +99,7 @@ export class Faucet {
     return this.tokenConfig.bankTokens.map((token) => token.tickerSymbol);
   }
 
-  public async loadAccounts(): Promise<ReadonlyArray<MinimalAccount>> {
+  public async loadAccounts(): Promise<readonly MinimalAccount[]> {
     const addresses = [this.holderAddress, ...this.distributorAddresses];
 
     return Promise.all(
diff --git a/packages/faucet/src/profile.ts b/packages/faucet/src/profile.ts
index 7aaf70e8..0abc05a9 100644
--- a/packages/faucet/src/profile.ts
+++ b/packages/faucet/src/profile.ts
@@ -6,8 +6,8 @@ export async function createPens(
   addressPrefix: string,
   numberOfDistributors: number,
   logging = false,
-): Promise<readonly [string, Pen][]> {
-  const pens = new Array<[string, Pen]>();
+): Promise<ReadonlyArray<readonly [string, Pen]>> {
+  const pens = new Array<readonly [string, Pen]>();
 
   // first account is the token holder
   const numberOfIdentities = 1 + numberOfDistributors;
diff --git a/packages/faucet/src/types.ts b/packages/faucet/src/types.ts
index ec2cbcde..f099fcd5 100644
--- a/packages/faucet/src/types.ts
+++ b/packages/faucet/src/types.ts
@@ -26,7 +26,7 @@ export interface BankTokenMeta {
 
 export interface TokenConfiguration {
   /** Supported tokens of the Cosmos SDK bank module */
-  readonly bankTokens: ReadonlyArray<BankTokenMeta>;
+  readonly bankTokens: readonly BankTokenMeta[];
 }
 
 export type MinimalAccount = Pick<Account, "address" | "balance">;
diff --git a/packages/sdk38/src/cosmosclient.ts b/packages/sdk38/src/cosmosclient.ts
index fc6fd5b5..077e354c 100644
--- a/packages/sdk38/src/cosmosclient.ts
+++ b/packages/sdk38/src/cosmosclient.ts
@@ -16,7 +16,7 @@ export interface GetNonceResult {
 export interface Account {
   /** Bech32 account address */
   readonly address: string;
-  readonly balance: ReadonlyArray<Coin>;
+  readonly balance: readonly Coin[];
   readonly pubkey: PubKey | undefined;
   readonly accountNumber: number;
   readonly sequence: number;
@@ -61,7 +61,7 @@ export interface SearchBySentFromOrToQuery {
  * more powerful and slightly lower level than the other search options.
  */
 export interface SearchByTagsQuery {
-  readonly tags: readonly { readonly key: string; readonly value: string }[];
+  readonly tags: ReadonlyArray<{ readonly key: string; readonly value: string }>;
 }
 
 export type SearchTxQuery =
@@ -125,7 +125,7 @@ export interface Block {
   readonly id: string;
   readonly header: BlockHeader;
   /** Array of raw transactions */
-  readonly txs: ReadonlyArray<Uint8Array>;
+  readonly txs: readonly Uint8Array[];
 }
 
 /** Use for testing only */
diff --git a/packages/sdk38/src/msgs.ts b/packages/sdk38/src/msgs.ts
index 83937893..8644eb6a 100644
--- a/packages/sdk38/src/msgs.ts
+++ b/packages/sdk38/src/msgs.ts
@@ -13,7 +13,7 @@ export interface MsgSend extends Msg {
     readonly from_address: string;
     /** Bech32 account address */
     readonly to_address: string;
-    readonly amount: ReadonlyArray<Coin>;
+    readonly amount: readonly Coin[];
   };
 }
 
diff --git a/packages/sdk38/src/restclient.ts b/packages/sdk38/src/restclient.ts
index 0cf8e62a..67edfb99 100644
--- a/packages/sdk38/src/restclient.ts
+++ b/packages/sdk38/src/restclient.ts
@@ -7,7 +7,7 @@ import { CosmosSdkTx, StdTx } from "./types";
 export interface CosmosSdkAccount {
   /** Bech32 account address */
   readonly address: string;
-  readonly coins: ReadonlyArray<Coin>;
+  readonly coins: readonly Coin[];
   /** Bech32 encoded pubkey */
   readonly public_key: string;
   readonly account_number: number;
@@ -84,7 +84,7 @@ interface Block {
   readonly header: BlockHeader;
   readonly data: {
     /** Array of base64 encoded transactions */
-    readonly txs: ReadonlyArray<string> | null;
+    readonly txs: readonly string[] | null;
   };
 }
 
diff --git a/packages/sdk38/src/types.ts b/packages/sdk38/src/types.ts
index e0c085a8..ecfea0c7 100644
--- a/packages/sdk38/src/types.ts
+++ b/packages/sdk38/src/types.ts
@@ -26,7 +26,7 @@ export interface CosmosSdkTx {
 }
 
 export interface StdFee {
-  readonly amount: ReadonlyArray<Coin>;
+  readonly amount: readonly Coin[];
   readonly gas: string;
 }
 
diff --git a/packages/sdk38/types/cosmosclient.d.ts b/packages/sdk38/types/cosmosclient.d.ts
index 4749f6b9..b62fb2c6 100644
--- a/packages/sdk38/types/cosmosclient.d.ts
+++ b/packages/sdk38/types/cosmosclient.d.ts
@@ -9,7 +9,7 @@ export interface GetNonceResult {
 export interface Account {
   /** Bech32 account address */
   readonly address: string;
-  readonly balance: ReadonlyArray<Coin>;
+  readonly balance: readonly Coin[];
   readonly pubkey: PubKey | undefined;
   readonly accountNumber: number;
   readonly sequence: number;
@@ -44,10 +44,10 @@ export interface SearchBySentFromOrToQuery {
  * more powerful and slightly lower level than the other search options.
  */
 export interface SearchByTagsQuery {
-  readonly tags: readonly {
+  readonly tags: ReadonlyArray<{
     readonly key: string;
     readonly value: string;
-  }[];
+  }>;
 }
 export declare type SearchTxQuery =
   | SearchByIdQuery
@@ -90,7 +90,7 @@ export interface Block {
   readonly id: string;
   readonly header: BlockHeader;
   /** Array of raw transactions */
-  readonly txs: ReadonlyArray<Uint8Array>;
+  readonly txs: readonly Uint8Array[];
 }
 /** Use for testing only */
 export interface PrivateCosmWasmClient {
diff --git a/packages/sdk38/types/msgs.d.ts b/packages/sdk38/types/msgs.d.ts
index eabba375..62221458 100644
--- a/packages/sdk38/types/msgs.d.ts
+++ b/packages/sdk38/types/msgs.d.ts
@@ -11,7 +11,7 @@ export interface MsgSend extends Msg {
     readonly from_address: string;
     /** Bech32 account address */
     readonly to_address: string;
-    readonly amount: ReadonlyArray<Coin>;
+    readonly amount: readonly Coin[];
   };
 }
 export declare function isMsgSend(msg: Msg): msg is MsgSend;
diff --git a/packages/sdk38/types/restclient.d.ts b/packages/sdk38/types/restclient.d.ts
index 830457cb..b1134d30 100644
--- a/packages/sdk38/types/restclient.d.ts
+++ b/packages/sdk38/types/restclient.d.ts
@@ -3,7 +3,7 @@ import { CosmosSdkTx, StdTx } from "./types";
 export interface CosmosSdkAccount {
   /** Bech32 account address */
   readonly address: string;
-  readonly coins: ReadonlyArray<Coin>;
+  readonly coins: readonly Coin[];
   /** Bech32 encoded pubkey */
   readonly public_key: string;
   readonly account_number: number;
@@ -69,7 +69,7 @@ interface Block {
   readonly header: BlockHeader;
   readonly data: {
     /** Array of base64 encoded transactions */
-    readonly txs: ReadonlyArray<string> | null;
+    readonly txs: readonly string[] | null;
   };
 }
 export interface BlockResponse {
diff --git a/packages/sdk38/types/types.d.ts b/packages/sdk38/types/types.d.ts
index 2f3d218d..c12484fa 100644
--- a/packages/sdk38/types/types.d.ts
+++ b/packages/sdk38/types/types.d.ts
@@ -17,7 +17,7 @@ export interface CosmosSdkTx {
   readonly value: StdTx;
 }
 export interface StdFee {
-  readonly amount: ReadonlyArray<Coin>;
+  readonly amount: readonly Coin[];
   readonly gas: string;
 }
 export interface StdSignature {
diff --git a/packages/stream/src/concat.ts b/packages/stream/src/concat.ts
index 131e080f..540bdbac 100644
--- a/packages/stream/src/concat.ts
+++ b/packages/stream/src/concat.ts
@@ -17,7 +17,7 @@ import { Producer, Stream, Subscription } from "xstream";
  * differently than xstream's concat as discussed in https://github.com/staltz/xstream/issues/170.
  *
  */
-export function concat<T>(...streams: Stream<T>[]): Stream<T> {
+export function concat<T>(...streams: Array<Stream<T>>): Stream<T> {
   const subscriptions = new Array<Subscription>();
   const queues = new Array<T[]>(); // one queue per stream
   const completedStreams = new Set<number>();
diff --git a/packages/stream/types/concat.d.ts b/packages/stream/types/concat.d.ts
index cd1ea4a5..132f6f62 100644
--- a/packages/stream/types/concat.d.ts
+++ b/packages/stream/types/concat.d.ts
@@ -16,4 +16,4 @@ import { Stream } from "xstream";
  * differently than xstream's concat as discussed in https://github.com/staltz/xstream/issues/170.
  *
  */
-export declare function concat<T>(...streams: Stream<T>[]): Stream<T>;
+export declare function concat<T>(...streams: Array<Stream<T>>): Stream<T>;