diff --git a/.gitignore b/.gitignore
index 4eeb802..9815f2f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 /node_modules
 /yarn.lock
-/package-lock.json
\ No newline at end of file
+/package-lock.json
+/pnpm-lock.yaml
\ No newline at end of file
diff --git a/package.json b/package.json
index 3209c00..07abb08 100644
--- a/package.json
+++ b/package.json
@@ -1,28 +1,28 @@
 {
   "name": "eslint-plugin-only-warn",
   "version": "1.1.0",
+  "license": "MIT",
   "description": "Downgrade errors to warnings",
   "keywords": [
     "eslint",
     "eslintplugin",
     "eslint-plugin"
   ],
-  "main": "src/only-warn.js",
-  "scripts": {
-    "test": "npm run lint && jest",
-    "lint": "prettier --check --loglevel=warn src tests && eslint src tests",
-    "format": "prettier --write --loglevel=warn src tests && eslint --fix src tests",
-    "jest:watch": "jest --watch"
-  },
   "author": "Bob Fanger",
   "homepage": "https://github.com/bfanger/eslint-plugin-only-warn",
   "repository": {
     "type": "git",
     "url": "https://github.com/bfanger/eslint-plugin-only-warn.git"
   },
-  "prettier": {
-    "semi": false,
-    "singleQuote": true
+  "engines": {
+    "node": ">=18"
+  },
+  "main": "src/only-warn.js",
+  "scripts": {
+    "lint": "prettier --check src tests && eslint src tests",
+    "format": "prettier --write src tests && eslint --fix src tests",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "eslintConfig": {
     "extends": "eslint:recommended",
@@ -38,15 +38,10 @@
       "prettier/prettier": "error"
     }
   },
-  "dependencies": {},
   "devDependencies": {
-    "eslint": "^7.31.0",
-    "eslint-plugin-prettier": "^3.1.2",
-    "jest": "^27.0.6",
-    "prettier": "^2.3.2"
-  },
-  "engines": {
-    "node": ">=6"
-  },
-  "license": "MIT"
+    "eslint": "^8.56.0",
+    "eslint-plugin-prettier": "^5.1.3",
+    "prettier": "^3.2.4",
+    "vitest": "^1.2.1"
+  }
 }
diff --git a/src/get-eslint-modules.js b/src/get-eslint-modules.js
index 5d0d13d..0314a4f 100644
--- a/src/get-eslint-modules.js
+++ b/src/get-eslint-modules.js
@@ -1,22 +1,22 @@
-const path = require('path')
+const path = require("path");
 
-const SEARCH_STR = `${path.sep}node_modules${path.sep}eslint${path.sep}`
+const SEARCH_STR = `${path.sep}node_modules${path.sep}eslint${path.sep}`;
 
 module.exports = function getEslintModules() {
-  const map = {}
+  const map = {};
   Object.keys(require.cache).forEach((modulePath) => {
-    const pos = modulePath.indexOf(SEARCH_STR)
+    const pos = modulePath.indexOf(SEARCH_STR);
     if (pos !== -1) {
-      const eslintPath = modulePath.substr(0, pos + SEARCH_STR.length)
+      const eslintPath = modulePath.substr(0, pos + SEARCH_STR.length);
       if (!map[eslintPath]) {
-        map[eslintPath] = require(eslintPath)
+        map[eslintPath] = require(eslintPath);
       }
     }
-  })
+  });
 
-  let modules = Object.values(map)
+  let modules = Object.values(map);
   if (modules.length === 0) {
-    modules = [require('eslint')]
+    modules = [require("eslint")];
   }
-  return modules
-}
+  return modules;
+};
diff --git a/src/only-warn.js b/src/only-warn.js
index 07b2090..44de93b 100644
--- a/src/only-warn.js
+++ b/src/only-warn.js
@@ -1,24 +1,24 @@
-const getEslintModules = require('./get-eslint-modules')
+const getEslintModules = require("./get-eslint-modules");
 
-const unpatchedVerify = Symbol('verify')
+const unpatchedVerify = Symbol("verify");
 
 /**
  * Patch the verify method and downgrade the errors to warnings.
  */
 function patch(LinterPrototype) {
   if (LinterPrototype[unpatchedVerify]) {
-    return
+    return;
   }
-  LinterPrototype[unpatchedVerify] = LinterPrototype.verify
+  LinterPrototype[unpatchedVerify] = LinterPrototype.verify;
   LinterPrototype.verify = function () {
-    const messages = LinterPrototype[unpatchedVerify].apply(this, arguments)
+    const messages = LinterPrototype[unpatchedVerify].apply(this, arguments);
     messages.forEach((message) => {
       if (!message.fatal && message.severity === 2) {
-        message.severity = 1
+        message.severity = 1;
       }
-    })
-    return messages
-  }
+    });
+    return messages;
+  };
 }
 
 /**
@@ -26,20 +26,20 @@ function patch(LinterPrototype) {
  */
 function unpatch(LinterPrototype) {
   if (LinterPrototype[unpatchedVerify]) {
-    LinterPrototype.verify = LinterPrototype[unpatchedVerify]
-    delete LinterPrototype[unpatchedVerify]
+    LinterPrototype.verify = LinterPrototype[unpatchedVerify];
+    delete LinterPrototype[unpatchedVerify];
   }
 }
 
 function enable() {
   for (const eslint of getEslintModules()) {
-    patch((eslint.Linter && eslint.Linter.prototype) || eslint.linter)
+    patch((eslint.Linter && eslint.Linter.prototype) || eslint.linter);
   }
 }
 function disable() {
   for (const eslint of getEslintModules()) {
-    unpatch((eslint.Linter && eslint.Linter.prototype) || eslint.linter)
+    unpatch((eslint.Linter && eslint.Linter.prototype) || eslint.linter);
   }
 }
-enable()
-module.exports = { enable, disable }
+enable();
+module.exports = { enable, disable };
diff --git a/tests/only-warn.spec.js b/tests/only-warn.spec.js
deleted file mode 100644
index 315b399..0000000
--- a/tests/only-warn.spec.js
+++ /dev/null
@@ -1,30 +0,0 @@
-const eslint = require('eslint')
-const { disable, enable } = require('../src/only-warn') // apply patch
-
-describe('eslint-plugin-only-warn', () => {
-  const linter = new eslint.Linter()
-  const config = {
-    rules: { semi: 2 }, // error on missing `;`
-  }
-  const sourceCode = 'var foo'
-  it('should downgrade error(2) to warn(1)', () => {
-    const messages = linter.verify(sourceCode, config)
-    expect(messages[0].severity).toBe(1)
-  })
-
-  const sourceCodeFatalError = 'var foo = ( => {}'
-  it('should not downgrade fatal error(2)', () => {
-    const messages = linter.verify(sourceCodeFatalError, config)
-    expect(messages[0].fatal).toBe(true)
-    expect(messages[0].severity).toBe(2)
-  })
-
-  it('can be temporarly disabled', () => {
-    disable()
-    const messages1 = linter.verify(sourceCode, config)
-    expect(messages1[0].severity).toBe(2)
-    enable()
-    const messages2 = linter.verify(sourceCode, config)
-    expect(messages2[0].severity).toBe(1)
-  })
-})
diff --git a/tests/only-warn.spec.ts b/tests/only-warn.spec.ts
new file mode 100644
index 0000000..4cbf50d
--- /dev/null
+++ b/tests/only-warn.spec.ts
@@ -0,0 +1,31 @@
+import { Linter } from "eslint";
+import { disable, enable } from "../src/only-warn"; // apply patch
+import { describe, it, expect } from "vitest";
+
+describe("eslint-plugin-only-warn", () => {
+  const linter = new Linter();
+  const config = {
+    rules: { semi: 2 }, // error on missing `;`
+  };
+  const sourceCode = "var foo";
+  it("should downgrade error(2) to warn(1)", () => {
+    const messages = linter.verify(sourceCode, config);
+    expect(messages[0].severity).toBe(1);
+  });
+
+  const sourceCodeFatalError = "var foo = ( => {}";
+  it("should not downgrade fatal error(2)", () => {
+    const messages = linter.verify(sourceCodeFatalError, config);
+    expect(messages[0].fatal).toBe(true);
+    expect(messages[0].severity).toBe(2);
+  });
+
+  it("can be temporarly disabled", () => {
+    disable();
+    const messages1 = linter.verify(sourceCode, config);
+    expect(messages1[0].severity).toBe(2);
+    enable();
+    const messages2 = linter.verify(sourceCode, config);
+    expect(messages2[0].severity).toBe(1);
+  });
+});