diff --git a/eslint.config.mjs b/eslint.config.mjs
index 10a99ce1..3b055296 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -62,7 +62,7 @@ export default [
         }
     },
     {
-        files: ["po/po2js", "po/xgettext-html"],
+        files: ["po/po2js.cjs", "po/xgettext-html.cjs"],
         languageOptions: {
             globals: {
                 ...globals.node,
diff --git a/karma.conf.js b/karma.conf.cjs
similarity index 100%
rename from karma.conf.js
rename to karma.conf.cjs
diff --git a/package.json b/package.json
index bfe16a54..8779797d 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "1.6.0",
   "description": "An HTML5 VNC client",
   "browser": "lib/rfb",
+  "type": "module",
   "directories": {
     "lib": "lib",
     "doc": "docs",
@@ -17,9 +18,9 @@
     "docs/LICENSE*"
   ],
   "scripts": {
-    "lint": "eslint app core po/po2js po/xgettext-html tests utils",
-    "test": "karma start karma.conf.js",
-    "prepublish": "node ./utils/convert.js --clean"
+    "lint": "eslint app core po/po2js.cjs po/xgettext-html.cjs tests utils",
+    "test": "karma start karma.conf.cjs",
+    "prepare": "node ./utils/convert.cjs --clean"
   },
   "repository": {
     "type": "git",
diff --git a/po/Makefile b/po/Makefile
index dcf5ba44..e31056b0 100644
--- a/po/Makefile
+++ b/po/Makefile
@@ -15,7 +15,7 @@ update-js: $(JSONFILES)
 %.po: FORCE
 	msgmerge --update --lang=$* $@ noVNC.pot
 ../app/locale/%.json: FORCE
-	./po2js $*.po $@
+	./po2js.cjs $*.po $@
 
 update-pot:
 	xgettext --output=noVNC.js.pot \
@@ -29,7 +29,7 @@ update-pot:
 		../app/*.js \
 		../core/*.js \
 		../core/input/*.js
-	./xgettext-html --output=noVNC.html.pot \
+	./xgettext-html.cjs --output=noVNC.html.pot \
 		../vnc.html
 	msgcat --output-file=noVNC.pot \
 		--sort-by-file noVNC.js.pot noVNC.html.pot
diff --git a/po/po2js b/po/po2js.cjs
similarity index 100%
rename from po/po2js
rename to po/po2js.cjs
diff --git a/po/xgettext-html b/po/xgettext-html.cjs
similarity index 100%
rename from po/xgettext-html
rename to po/xgettext-html.cjs
diff --git a/utils/convert.js b/utils/convert.cjs
similarity index 99%
rename from utils/convert.js
rename to utils/convert.cjs
index 617f4ed6..35dfe9e8 100755
--- a/utils/convert.js
+++ b/utils/convert.cjs
@@ -64,7 +64,7 @@ function makeLibFiles(sourceMaps) {
         plugins: [],
         presets: [
             [ '@babel/preset-env',
-              { modules: 'commonjs' } ]
+              { modules: false } ]
         ],
         ast: false,
         sourceMaps: sourceMaps,
diff --git a/utils/genkeysymdef.js b/utils/genkeysymdef.cjs
similarity index 100%
rename from utils/genkeysymdef.js
rename to utils/genkeysymdef.cjs