diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 08875ac9b1f..75f53724143 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -32,5 +32,3 @@ updates:
         update-types: ["version-update:semver-major"]
       - dependency-name: "chai-as-promised"
         update-types: ["version-update:semver-major"]
-      - dependency-name: "filesize"
-        versions: [ ">= 10.1.3" ]
diff --git a/extension/chrome/elements/pgp_block.htm b/extension/chrome/elements/pgp_block.htm
index f8f07a16198..ed3c39c3bfb 100644
--- a/extension/chrome/elements/pgp_block.htm
+++ b/extension/chrome/elements/pgp_block.htm
@@ -41,7 +41,6 @@
     <script src="/lib/sweetalert2.js"></script>
     <script src="/lib/linkify.min.js"></script>
     <script src="/lib/linkify-html.min.js"></script>
-    <script src="/lib/filesize.js"></script>
     <script src="pgp_block.js" type="module"></script>
   </body>
 </html>
diff --git a/extension/chrome/elements/pgp_block_modules/pgp-block-attachments-module.ts b/extension/chrome/elements/pgp_block_modules/pgp-block-attachments-module.ts
index add3d36856c..11829a30b7f 100644
--- a/extension/chrome/elements/pgp_block_modules/pgp-block-attachments-module.ts
+++ b/extension/chrome/elements/pgp_block_modules/pgp-block-attachments-module.ts
@@ -14,8 +14,7 @@ import { XssSafeFactory } from '../../../js/common/xss-safe-factory.js';
 import { Str } from '../../../js/common/core/common.js';
 import { AttachmentWarnings } from '../shared/attachment_warnings.js';
 import { MsgUtil } from '../../../js/common/core/crypto/pgp/msg-util.js';
-
-declare const filesize: { filesize: (size: number) => number };
+import { filesize } from 'filesize';
 
 export class PgpBlockViewAttachmentsModule {
   public includedAttachments: Attachment[] = [];
@@ -28,7 +27,9 @@ export class PgpBlockViewAttachmentsModule {
     for (const i of attachments.keys()) {
       const name = attachments[i].name ? Str.stripPgpOrGpgExtensionIfPresent(attachments[i].name) : 'noname';
       const nameVisible = name.length > 100 ? name.slice(0, 100) + '…' : name;
-      const size = filesize.filesize(attachments[i].length);
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-call
+      const size = filesize(attachments[i].length);
+
       const htmlContent = `<b>${Xss.escape(nameVisible)}</b>&nbsp;&nbsp;&nbsp;${size}<span class="progress"><span class="percent"></span></span>`;
       const attachment = $(`<a href="#" index="${Number(i)}">`);
       attachment.attr('title', name);
diff --git a/package-lock.json b/package-lock.json
index c3257df0399..18c5a03e0ee 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -15,7 +15,7 @@
         "bootstrap": "4.6.2",
         "clipboard": "2.0.11",
         "dompurify": "3.2.5",
-        "filesize": "10.1.2",
+        "filesize": "10.1.6",
         "fs-extra": "^11.3.0",
         "globby": "^14.1.0",
         "iso-8859-2": "1.0.0",
@@ -5101,9 +5101,9 @@
       }
     },
     "node_modules/filesize": {
-      "version": "10.1.2",
-      "resolved": "https://registry.npmjs.org/filesize/-/filesize-10.1.2.tgz",
-      "integrity": "sha512-Dx770ai81ohflojxhU+oG+Z2QGvKdYxgEr9OSA8UVrqhwNHjfH9A8f5NKfg83fEH8ZFA5N5llJo5T3PIoZ4CRA==",
+      "version": "10.1.6",
+      "resolved": "https://registry.npmjs.org/filesize/-/filesize-10.1.6.tgz",
+      "integrity": "sha512-sJslQKU2uM33qH5nqewAwVB2QgR6w1aMNsYUp3aN5rMRyXEwJGmZvaWzeJFNTOXWlHQyBFCWrdj3fV/fsTOX8w==",
       "license": "BSD-3-Clause",
       "engines": {
         "node": ">= 10.4.0"
diff --git a/package.json b/package.json
index a2fbbc0967c..807fe40a487 100644
--- a/package.json
+++ b/package.json
@@ -48,7 +48,7 @@
     "bootstrap": "4.6.2",
     "clipboard": "2.0.11",
     "dompurify": "3.2.5",
-    "filesize": "10.1.2",
+    "filesize": "10.1.6",
     "fs-extra": "^11.3.0",
     "globby": "^14.1.0",
     "iso-8859-2": "1.0.0",
diff --git a/scripts/build.js b/scripts/build.js
index ceecdb1091e..2cde8736111 100644
--- a/scripts/build.js
+++ b/scripts/build.js
@@ -62,7 +62,7 @@ const copyDependencies = async () => {
     ['squire-rte/dist/squire.js', 'lib/squire.js'],
     ['clipboard/dist/clipboard.js', 'lib/clipboard.js'],
     ['@flowcrypt/fine-uploader/fine-uploader/fine-uploader.js', 'lib/fine-uploader.js'],
-    ['filesize/dist/filesize.js', 'lib/filesize.js'],
+    ['filesize/dist/filesize.esm.js', 'lib/filesize.js'],
     // Using legacy build due to Puppeteer compatibility issue (Promise.withResolvers error)
     // Reference: https://github.com/mozilla/pdf.js/issues/18006#issuecomment-2078739672
     ['pdfjs-dist/legacy/build/pdf.min.mjs', 'lib/pdf.min.mjs'],
diff --git a/tsconfig.json b/tsconfig.json
index 2aad19adba8..aff23c223e6 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -27,7 +27,7 @@
       "dompurify": ["../node_modules/dompurify/dist/purify.cjs.d.ts", "lib/purify.js", "COMMENT"],
       "fine-uploader": ["lib/fine-uploader.js", "COMMENT"],
       "clipboard": ["lib/clipboard.js", "COMMENT"],
-      "filesize": ["lib/filesize.js", "COMMENT"],
+      "filesize": ["lib/filesize.js", "../node_modules/filesize/types/filesize.d.ts"],
       "iso-8859-2": ["lib/iso-8859-2.js", "COMMENT"],
       "zxcvbn": ["lib/zxcvbn.js", "COMMENT"],
       "emailjs-mime-parser": ["lib/emailjs/emailjs-mime-parser.js", "COMMENT"],