diff --git a/chrome/content/zotero/EPUB.jsm b/chrome/content/zotero/EPUB.mjs
similarity index 99%
rename from chrome/content/zotero/EPUB.jsm
rename to chrome/content/zotero/EPUB.mjs
index 71f12f19c1..631cc348bc 100644
--- a/chrome/content/zotero/EPUB.jsm
+++ b/chrome/content/zotero/EPUB.mjs
@@ -23,8 +23,6 @@
     ***** END LICENSE BLOCK *****
 */
 
-var EXPORTED_SYMBOLS = ["EPUB"];
-
 ChromeUtils.defineESModuleGetters(this, {
 	Zotero: "chrome://zotero/content/zotero.mjs",
 });
@@ -38,7 +36,7 @@ const ZipReader = Components.Constructor(
 const DC_NS = 'http://purl.org/dc/elements/1.1/';
 const OPF_NS = 'http://www.idpf.org/2007/opf';
 
-class EPUB {
+export class EPUB {
 	_zipReader;
 
 	_contentOPF = null;
diff --git a/chrome/content/zotero/xpcom/fulltext.js b/chrome/content/zotero/xpcom/fulltext.js
index b593af610d..52ee6428a7 100644
--- a/chrome/content/zotero/xpcom/fulltext.js
+++ b/chrome/content/zotero/xpcom/fulltext.js
@@ -411,7 +411,7 @@ Zotero.Fulltext = Zotero.FullText = new function () {
 	 * @return {Promise}
 	 */
 	this.indexEPUB = async function (filePath, itemID, allText) {
-		const { EPUB } = ChromeUtils.import('chrome://zotero/content/EPUB.jsm');
+		const { EPUB } = ChromeUtils.importESModule("chrome://zotero/content/EPUB.mjs");
 		
 		let maxLength = Zotero.Prefs.get('fulltext.textMaxLength');
 		if (maxLength === 0) {
diff --git a/chrome/content/zotero/xpcom/recognizeDocument.js b/chrome/content/zotero/xpcom/recognizeDocument.js
index 1ac1173d39..9cc21abcca 100644
--- a/chrome/content/zotero/xpcom/recognizeDocument.js
+++ b/chrome/content/zotero/xpcom/recognizeDocument.js
@@ -578,7 +578,7 @@ Zotero.RecognizeDocument = new function () {
 	}
 	
 	async function _recognizeEPUB(item, filePath) {
-		const { EPUB } = ChromeUtils.import('chrome://zotero/content/EPUB.jsm');
+		const { EPUB } = ChromeUtils.importESModule("chrome://zotero/content/EPUB.mjs");
 		
 		let epub = new EPUB(filePath);
 		try {