diff --git a/package.json b/package.json
index 632b81c..92680d9 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
     "lint": "aegir lint",
     "build": "aegir build",
     "pregenerate:types": "rimraf './src/**/*.d.ts'",
-    "generate:types": "tsc",
+    "generate:types": "tsc --build",
     "test": "aegir test",
     "test:node": "aegir test --target node",
     "test:browser": "aegir test --target browser",
@@ -69,7 +69,7 @@
     "aegir": "^25.0.0",
     "it-handshake": "^1.0.1",
     "rimraf": "^3.0.2",
-    "typescript": "^4.1.2"
+    "typescript": "^4.0.5"
   },
   "contributors": [
     "Alan Shaw <alan.shaw@protocol.ai>",
diff --git a/src/pubsub/utils.d.ts b/src/pubsub/utils.d.ts
index c400623..3a95fdd 100644
--- a/src/pubsub/utils.d.ts
+++ b/src/pubsub/utils.d.ts
@@ -3,11 +3,11 @@ export function msgId(from: string, seqno: Uint8Array): Uint8Array;
 export function noSignMsgId(data: Uint8Array): Uint8Array;
 export function anyMatch(a: Set<any> | any[], b: Set<any> | any[]): boolean;
 export function ensureArray<T>(maybeArray: T | T[]): T[];
-export function normalizeInRpcMessage<T extends Object>(message: T, peerId?: string | undefined): T & {
+export function normalizeInRpcMessage<T extends unknown>(message: T, peerId?: string | undefined): T & {
     from?: string | undefined;
     peerId?: string | undefined;
 };
-export function normalizeOutRpcMessage<T extends Object>(message: T): T & {
+export function normalizeOutRpcMessage<T extends unknown>(message: T): T & {
     from?: Uint8Array | undefined;
     data?: Uint8Array | undefined;
 };
diff --git a/src/topology/index.d.ts b/src/topology/index.d.ts
index 83bc5c9..21b300d 100644
--- a/src/topology/index.d.ts
+++ b/src/topology/index.d.ts
@@ -8,22 +8,9 @@ declare class Topology {
      */
     static isTopology(other: any): other is Topology;
     /**
-     * @param {Object} props
-     * @param {number} [props.min] minimum needed connections (default: 0)
-     * @param {number} [props.max] maximum needed connections (default: Infinity)
-     * @param {Object} [props.handlers]
-     * @param {function} [props.handlers.onConnect] protocol "onConnect" handler
-     * @param {function} [props.handlers.onDisconnect] protocol "onDisconnect" handler
-     * @constructor
+     * @param {Options} options
      */
-    constructor({ min, max, handlers }: {
-        min: number | undefined;
-        max: number | undefined;
-        handlers: {
-            onConnect?: Function | undefined;
-            onDisconnect?: Function | undefined;
-        } | undefined;
-    });
+    constructor({ min, max, handlers }: Options);
     min: number;
     max: number;
     _onConnect: Function;
@@ -48,4 +35,28 @@ declare class Topology {
     disconnect(peerId: import("peer-id")): void;
     get [topologySymbol](): boolean;
 }
+declare namespace Topology {
+    export { Options, Handlers };
+}
 declare const topologySymbol: unique symbol;
+type Options = {
+    /**
+     * - minimum needed connections.
+     */
+    min?: number | undefined;
+    /**
+     * - maximum needed connections.
+     */
+    max?: number | undefined;
+    handlers?: Handlers | undefined;
+};
+type Handlers = {
+    /**
+     * - protocol "onConnect" handler
+     */
+    onConnect?: Function | undefined;
+    /**
+     * - protocol "onDisconnect" handler
+     */
+    onDisconnect?: Function | undefined;
+};
diff --git a/src/topology/index.js b/src/topology/index.js
index ef36c5c..4dc651b 100644
--- a/src/topology/index.js
+++ b/src/topology/index.js
@@ -6,13 +6,7 @@ const topologySymbol = Symbol.for('@libp2p/js-interfaces/topology')
 
 class Topology {
   /**
-   * @param {Object} props
-   * @param {number} [props.min] minimum needed connections (default: 0)
-   * @param {number} [props.max] maximum needed connections (default: Infinity)
-   * @param {Object} [props.handlers]
-   * @param {function} [props.handlers.onConnect] protocol "onConnect" handler
-   * @param {function} [props.handlers.onDisconnect] protocol "onDisconnect" handler
-   * @constructor
+   * @param {Options} options
    */
   constructor ({
     min = 0,
@@ -70,4 +64,15 @@ class Topology {
   }
 }
 
+/**
+ * @typedef {Object} Options
+ * @property {number} [min=0] - minimum needed connections.
+ * @property {number} [max=Infinity] - maximum needed connections.
+ * @property {Handlers} [handlers]
+ *
+ * @typedef {Object} Handlers
+ * @property {Function} [onConnect] - protocol "onConnect" handler
+ * @property {Function} [onDisconnect] - protocol "onDisconnect" handler
+ */
+
 module.exports = Topology
diff --git a/src/topology/multicodec-topology.d.ts b/src/topology/multicodec-topology.d.ts
index 343e3f1..4a52993 100644
--- a/src/topology/multicodec-topology.d.ts
+++ b/src/topology/multicodec-topology.d.ts
@@ -8,24 +8,9 @@ declare class MulticodecTopology extends Topology {
      */
     static isMulticodecTopology(other: any): other is MulticodecTopology;
     /**
-     * @param {Object} props
-     * @param {number} [props.min] minimum needed connections (default: 0)
-     * @param {number} [props.max] maximum needed connections (default: Infinity)
-     * @param {Array<string>} props.multicodecs protocol multicodecs
-     * @param {Object} props.handlers
-     * @param {function} props.handlers.onConnect protocol "onConnect" handler
-     * @param {function} props.handlers.onDisconnect protocol "onDisconnect" handler
-     * @constructor
+     * @param {TopologyOptions & MulticodecOptions} props
      */
-    constructor({ min, max, multicodecs, handlers }: {
-        min: number | undefined;
-        max: number | undefined;
-        multicodecs: Array<string>;
-        handlers: {
-            onConnect: Function;
-            onDisconnect: Function;
-        };
-    });
+    constructor({ min, max, multicodecs, handlers }: TopologyOptions & MulticodecOptions);
     multicodecs: string[];
     /**
      * Check if a new peer support the multicodecs for this topology.
@@ -53,11 +38,41 @@ declare class MulticodecTopology extends Topology {
         multiaddrs: Array<Multiaddr>;
         protocols: Array<string>;
     }>): void;
+    get [multicodecTopologySymbol](): boolean;
 }
 declare namespace MulticodecTopology {
-    export { PeerId, Multiaddr, Connection };
+    export { PeerId, Multiaddr, Connection, TopologyOptions, MulticodecOptions, Handlers };
 }
 import Topology = require(".");
 type PeerId = import("peer-id");
 type Connection = typeof import("../connection");
 type Multiaddr = import("multiaddr");
+declare const multicodecTopologySymbol: unique symbol;
+type TopologyOptions = {
+    /**
+     * - minimum needed connections.
+     */
+    min?: number | undefined;
+    /**
+     * - maximum needed connections.
+     */
+    max?: number | undefined;
+    handlers?: Topology.Handlers | undefined;
+};
+type MulticodecOptions = {
+    /**
+     * - protocol multicodecs
+     */
+    multicodecs: string[];
+    handlers: Required<Handlers>;
+};
+type Handlers = {
+    /**
+     * - protocol "onConnect" handler
+     */
+    onConnect?: Function | undefined;
+    /**
+     * - protocol "onDisconnect" handler
+     */
+    onDisconnect?: Function | undefined;
+};
diff --git a/src/topology/multicodec-topology.js b/src/topology/multicodec-topology.js
index 271f25e..c46d23d 100644
--- a/src/topology/multicodec-topology.js
+++ b/src/topology/multicodec-topology.js
@@ -6,14 +6,7 @@ const multicodecTopologySymbol = Symbol.for('@libp2p/js-interfaces/topology/mult
 
 class MulticodecTopology extends Topology {
   /**
-   * @param {Object} props
-   * @param {number} [props.min] minimum needed connections (default: 0)
-   * @param {number} [props.max] maximum needed connections (default: Infinity)
-   * @param {Array<string>} props.multicodecs protocol multicodecs
-   * @param {Object} props.handlers
-   * @param {function} props.handlers.onConnect protocol "onConnect" handler
-   * @param {function} props.handlers.onDisconnect protocol "onDisconnect" handler
-   * @constructor
+   * @param {TopologyOptions & MulticodecOptions} props
    */
   constructor ({
     min,
@@ -143,5 +136,10 @@ class MulticodecTopology extends Topology {
  * @typedef {import('peer-id')} PeerId
  * @typedef {import('multiaddr')} Multiaddr
  * @typedef {import('../connection')} Connection
+ * @typedef {import('.').Options} TopologyOptions
+ * @typedef {Object} MulticodecOptions
+ * @property {string[]} multicodecs - protocol multicodecs
+ * @property {Required<Handlers>} handlers
+ * @typedef {import('.').Handlers} Handlers
  */
 module.exports = MulticodecTopology
diff --git a/tsconfig.json b/tsconfig.json
index 2902998..9b19b9a 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -6,7 +6,20 @@
     // Tells TypeScript to read JS files, as
     // normally they are ignored as source files
     "allowJs": true,
+    "forceConsistentCasingInFileNames": true,
+    "noImplicitReturns": false,
+    "noImplicitAny": false, 
+    "noImplicitThis": true,
+    "noFallthroughCasesInSwitch": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": false,
+    "strictFunctionTypes": true,
+    "strictNullChecks": true,
+    "strictPropertyInitialization": true,
+    "strictBindCallApply": true,
     "strict": true,
+    "alwaysStrict": true,
+    "stripInternal": true,
     // Generate d.ts files
     "declaration": true,
     // This compiler run should