diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9806c99..2d3ecbc 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -186,12 +186,6 @@ jobs:
     - name: Install Node.js dependencies
       run: npm install
 
-    - name: Install browserify
-      run: |
-        if [[ "$(cut -d. -f1 <<< "${{ matrix.node-version }}")" -ge 1 ]]; then
-          npm install --save-dev browserify@16
-        fi
-
     - name: List environment
       id: list_env
       shell: bash
diff --git a/.github/workflows/upstream.yml b/.github/workflows/upstream.yml
new file mode 100644
index 0000000..9f6c1ec
--- /dev/null
+++ b/.github/workflows/upstream.yml
@@ -0,0 +1,25 @@
+name: upstream
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "33 3 * * 3"  # weekly
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: ['latest']
+    steps:
+      - uses: actions/checkout@v4
+      - name: Use Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+      - run: npm install
+      - run: npm run upstream
diff --git a/package.json b/package.json
index 03fb940..6a0316e 100644
--- a/package.json
+++ b/package.json
@@ -34,9 +34,10 @@
   },
   "scripts": {
     "lint": "eslint --plugin markdown --ext js,md .",
-    "test": "mocha --reporter spec --bail --check-leaks test/",
+    "test": "mocha --reporter spec --bail --check-leaks test/test.js",
     "test-ci": "nyc --reporter=lcov --reporter=text npm test",
     "test-cov": "nyc --reporter=html --reporter=text npm test",
+    "upstream": "mocha --reporter spec --check-leaks test/upstream.js",
     "version": "node scripts/version-history.js && git add HISTORY.md"
   }
 }
diff --git a/test/upstream.js b/test/upstream.js
new file mode 100644
index 0000000..e997a45
--- /dev/null
+++ b/test/upstream.js
@@ -0,0 +1,42 @@
+// NOTE: this is a temporary solution to tell us if future changes to the monkey-patched methods
+// could impact this package. Recognizing this is not an ideal solution, we plan to address this when
+// we can drop the monkey-patching entirely.
+const crypto = require('crypto')
+const assert = require('assert')
+const http = require('http')
+const Socket = require('net').Socket
+
+const req = new http.IncomingMessage(new Socket())
+const res = new http.ServerResponse(req)
+
+function getFunctionHash (fn) {
+  const src = fn.toString().replace(/\s+/g, '') // normalize whitespace
+  return crypto.createHash('sha256').update(src).digest('hex')
+}
+
+const knownWriteHeadHash = '281e0d02084a69893b8c3b8692e3c7c4de2ce22a626217fcf597fa6ddf6955a9'
+const knownSetHeaderHash = '2d4f95e92586d28bfd4d3137a8eaacb82b255967d8c26413015c6b56daf0afe7'
+const knownAppendHeaderHash = '0deb9f70c3bba63993321cca9281fb4607e2567bed1436b8574c5b86698125a8'
+const knownRemoveHeaderHash = '3ad5ccb0a858beb6268f281492bd8d42c9815f5316cc3c4f7f735e142fcd29d9'
+
+describe('function verification', function () {
+  it('should match the known function hash of writeHead', function () {
+    const currentHash = getFunctionHash(res.writeHead)
+    assert.strictEqual(currentHash, knownWriteHeadHash, 'writeHead hash has changed')
+  })
+
+  it('should match the known function hash of setHeader', function () {
+    const currentHash = getFunctionHash(res.setHeader)
+    assert.strictEqual(currentHash, knownSetHeaderHash, 'setHeader hash has changed')
+  })
+
+  it('should match the known function hash of appendHeader', function () {
+    const currentHash = getFunctionHash(res.appendHeader)
+    assert.strictEqual(currentHash, knownAppendHeaderHash, 'appendHeader hash has changed')
+  })
+
+  it('should match the known function hash of removeHeader', function () {
+    const currentHash = getFunctionHash(res.removeHeader)
+    assert.strictEqual(currentHash, knownRemoveHeaderHash, 'removeHeader hash has changed')
+  })
+})