diff --git a/package-lock.json b/package-lock.json
index faab1da1..3c7b1b6c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4013,9 +4013,9 @@
       "dev": true
     },
     "typescript": {
-      "version": "5.0.4",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.0.4.tgz",
-      "integrity": "sha512-cW9T5W9xY37cc+jfEnaUvX91foxtHkza3Nw3wkoF4sSlKn0MONdkdEndig/qPBWXNkmplh3NzayQzCiHM4/hqw==",
+      "version": "5.6.2",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.6.2.tgz",
+      "integrity": "sha512-NW8ByodCSNCwZeghjN3o+JX5OFH0Ojg6sadjEKY4huZ52TqbJTJnDo5+Tw98lSy63NZvi4n+ez5m2u5d4PkZyw==",
       "dev": true
     },
     "undici-types": {
diff --git a/package.json b/package.json
index 8c272ee8..d2200af3 100644
--- a/package.json
+++ b/package.json
@@ -39,7 +39,7 @@
     "eslint": "^8.57.0",
     "jest": "^28.1.3",
     "ts-jest": "^28.0.8",
-    "typescript": "^5.0.4"
+    "typescript": "^5.6.2"
   },
   "files": [
     ".editorconfig",
diff --git a/src/io.ts b/src/io.ts
index cf98df53..7d355605 100644
--- a/src/io.ts
+++ b/src/io.ts
@@ -40,7 +40,7 @@ export const writeFile = async (
     await mkdirRetry(dir);
   }
   let fileData: Uint8Array | string;
-  let options: ObjectEncodingOptions | void;
+  let options: ObjectEncodingOptions | void = void 0;
   if (typeof data === 'string') {
     fileData = data;
     options = {encoding};
diff --git a/src/life-cycle/download-resource.ts b/src/life-cycle/download-resource.ts
index f0ee1e6b..a43c123f 100644
--- a/src/life-cycle/download-resource.ts
+++ b/src/life-cycle/download-resource.ts
@@ -51,13 +51,13 @@ export async function getRetry(
   url: string,
   options: Options
 ): Promise<Response<Buffer | string> | void> {
-  let res: Response<Buffer | string> | void;
-  let err: DownloadError | void, optionsClone: Options;
+  let res: Response<Buffer | string> | void = void 0;
+  let err: DownloadError | void = void 0, optionsClone: Options;
   for (let i = 0; i < 25; i++) {
     err = void 0;
     try {
       optionsClone = Object.assign({}, options);
-      res = (await got(url, optionsClone)) as typeof res;
+      res = (await got(url, optionsClone)) as Response<Buffer | string>;
       if (!res || !res.body || !res.body.length) {
         logger.retry.warn(i, url, 'manually retry on empty response or body',
           res && res.body);
diff --git a/src/life-cycle/download-streaming-resource.ts b/src/life-cycle/download-streaming-resource.ts
index 9ceabe11..0a00ccd7 100644
--- a/src/life-cycle/download-streaming-resource.ts
+++ b/src/life-cycle/download-streaming-resource.ts
@@ -222,7 +222,7 @@ export async function optionallySetLastModifiedTime(
   res: Resource, options: StaticDownloadOptions
 ): Promise<void> {
   // https://github.com/website-local/website-scrap-engine/issues/174
-  let mtime: number | void;
+  let mtime: number | void = void 0;
   if (options.preferRemoteLastModifiedTime && res.meta?.headers?.['last-modified']) {
     mtime = Date.parse(res.meta.headers?.['last-modified']);
   }
diff --git a/src/life-cycle/read-or-copy-local-resource.ts b/src/life-cycle/read-or-copy-local-resource.ts
index 7718e2ae..6e8eb655 100644
--- a/src/life-cycle/read-or-copy-local-resource.ts
+++ b/src/life-cycle/read-or-copy-local-resource.ts
@@ -27,7 +27,7 @@ export async function readOrCopyLocalResource(
     return;
   }
   // index.html handling
-  let stats: Stats | void;
+  let stats: Stats | void = void 0;
   if (res.type === ResourceType.Html) {
     stats = await promises.stat(fileSrcPath);
     if (stats.isDirectory()) {
diff --git a/src/life-cycle/save-html-to-disk.ts b/src/life-cycle/save-html-to-disk.ts
index 7fb73feb..9031019d 100644
--- a/src/life-cycle/save-html-to-disk.ts
+++ b/src/life-cycle/save-html-to-disk.ts
@@ -46,7 +46,7 @@ export async function saveHtmlToDisk(
   }
   const localRoot: string = res.localRoot ?? options.localRoot;
   // https://github.com/website-local/website-scrap-engine/issues/174
-  let mtime: number | void;
+  let mtime: number | void = void 0;
   if (options.preferRemoteLastModifiedTime && res.meta?.headers?.['last-modified']) {
     mtime = Date.parse(res.meta.headers?.['last-modified']);
   }
diff --git a/src/life-cycle/save-resource-to-disk.ts b/src/life-cycle/save-resource-to-disk.ts
index fe69c97a..adb97071 100644
--- a/src/life-cycle/save-resource-to-disk.ts
+++ b/src/life-cycle/save-resource-to-disk.ts
@@ -10,7 +10,7 @@ export async function saveResourceToDisk(
   pipeline: PipelineExecutor): Promise<DownloadResource | void> {
   const localRoot: string = res.localRoot ?? options.localRoot;
   // https://github.com/website-local/website-scrap-engine/issues/174
-  let mtime: number | void;
+  let mtime: number | void = void 0;
   if (options.preferRemoteLastModifiedTime && res.meta?.headers?.['last-modified']) {
     mtime = Date.parse(res.meta.headers?.['last-modified']);
   }