diff --git a/jest.config.js b/jest.config.js
new file mode 100644
index 00000000..9491a44d
--- /dev/null
+++ b/jest.config.js
@@ -0,0 +1,17 @@
+/**  @type {import('@jest/types').Config.ProjectConfig} */
+const config = {
+  transform: {
+    '\\.[jt]sx?$': 'ts-jest',
+  },
+  'globals': {
+    'ts-jest': {
+      'useESM': true
+    }
+  },
+  moduleNameMapper: {
+    '^\\.(.+)\\.js': '.$1'
+  },
+  extensionsToTreatAsEsm: ['.ts'],
+};
+
+module.exports = config;
diff --git a/package.json b/package.json
index 7d4a1c0d..08739f70 100644
--- a/package.json
+++ b/package.json
@@ -17,9 +17,6 @@
     "prepack": "npm run clean && npm run build",
     "postshrinkwrap": "node package-lock-resolved.js"
   },
-  "jest": {
-    "preset": "ts-jest"
-  },
   "dependencies": {
     "cheerio": "^1.0.0",
     "css-url-parser": "^1.1.3",
diff --git a/tsconfig.json b/tsconfig.json
index dfe9adcd..46256dac 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -9,7 +9,8 @@
     "esModuleInterop": true,
     "removeComments": false,
     "strict": true,
-    "declarationMap": true
+    "declarationMap": true,
+    "allowJs": true
   },
   "include": [
     "src"