diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 828ba06..e2d8dc3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,9 +12,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Install Node.js
-      uses: actions/setup-node@v3
+      uses: actions/setup-node@v4
       with:
         node-version: 16
     - name: Install Packages
@@ -30,7 +30,7 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         eslint: [6, 7, 8]
-        node: [12.22.0, 14, 16, 17, 18, 19, 20, 21]
+        node: [14, 16, 17, 18, 19, 20, 21]
         include:
           - os: windows-latest
             eslint: 7
@@ -41,9 +41,9 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Install Node.js ${{ matrix.node }}
-      uses: actions/setup-node@v3
+      uses: actions/setup-node@v4
       with:
         node-version: ${{ matrix.node }}
     - name: Install Packages
diff --git a/.github/workflows/release-please.yml b/.github/workflows/release-please.yml
index dc0b6f5..185d57e 100644
--- a/.github/workflows/release-please.yml
+++ b/.github/workflows/release-please.yml
@@ -29,9 +29,9 @@ jobs:
               { "type": "refactor", "section": "Chores", "hidden": false },
               { "type": "test", "section": "Chores", "hidden": false }
             ]
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         if: ${{ steps.release.outputs.release_created }}
-      - uses: actions/setup-node@v3
+      - uses: actions/setup-node@v4
         with:
           node-version: lts/*
           registry-url: https://registry.npmjs.org
diff --git a/lib/processor.js b/lib/processor.js
index 63aa915..c1661d8 100644
--- a/lib/processor.js
+++ b/lib/processor.js
@@ -28,7 +28,9 @@
 
 "use strict";
 
-const parse = require("mdast-util-from-markdown");
+const { createSyncFn } = require("synckit");
+
+const parse = createSyncFn(require.resolve("./worker.mjs"));
 
 const UNSATISFIABLE_RULES = [
     "eol-last", // The Markdown parser strips trailing newlines in code fences
diff --git a/lib/worker.mjs b/lib/worker.mjs
new file mode 100644
index 0000000..ba06136
--- /dev/null
+++ b/lib/worker.mjs
@@ -0,0 +1,9 @@
+import { fromMarkdown } from "mdast-util-from-markdown";
+import { runAsWorker } from "synckit";
+
+runAsWorker(
+    /**
+     * @param {string} text
+     */
+    (text) => fromMarkdown(text)
+);
diff --git a/package.json b/package.json
index 7446546..79aaab9 100644
--- a/package.json
+++ b/package.json
@@ -33,7 +33,8 @@
   "files": [
     "index.js",
     "lib/index.js",
-    "lib/processor.js"
+    "lib/processor.js",
+    "lib/worker.mjs"
   ],
   "devDependencies": {
     "chai": "^4.2.0",
@@ -46,12 +47,13 @@
     "nyc": "^14.1.1"
   },
   "dependencies": {
-    "mdast-util-from-markdown": "^0.8.5"
+    "mdast-util-from-markdown": "^2.0.0",
+    "synckit": "^0.8.5"
   },
   "peerDependencies": {
     "eslint": "^6.0.0 || ^7.0.0 || ^8.0.0"
   },
   "engines": {
-    "node": "^12.22.0 || ^14.17.0 || >=16.0.0"
+    "node": "^14.18.0 || >=16.0.0"
   }
 }