diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 551388fcc..665061af5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -48,7 +48,7 @@ jobs:
           - { node: '16', postgres: &stable_postgres '18' }
           - { node: '18', postgres: *stable_postgres }
           - { node: '20', postgres: *stable_postgres }
-          - { node: '22', postgres: *stable_postgres }
+          - { node: '22', postgres: *stable_postgres, coverage: true }
           - { node: '24', postgres: *stable_postgres }
           # Latest Node.js version tested against multiple PostgreSQL versions
           - { node: &latest_node '26', postgres: '13' }
@@ -92,4 +92,8 @@ jobs:
           node-version: ${{ matrix.node }}
           cache: yarn
       - run: yarn install --frozen-lockfile
-      - run: yarn test
+      - run: yarn ${{ matrix.coverage && 'coverage' || 'test' }}
+      - uses: coverallsapp/github-action@v2
+        if: ${{ matrix.coverage }}
+        with:
+          file: coverage/lcov.info
diff --git a/.gitignore b/.gitignore
index c6d5700ae..aecc1454f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,3 +11,6 @@ dist
 .vscode/
 manually-test-on-heroku.js
 tsconfig.tsbuildinfo
+
+coverage/
+.nyc_output/
diff --git a/.nycrc b/.nycrc
new file mode 100644
index 000000000..6e1d2f67e
--- /dev/null
+++ b/.nycrc
@@ -0,0 +1,14 @@
+{
+  "all": true,
+  "include": ["packages/*/index.js", "packages/*/lib/**", "packages/*/src/**", "packages/*/dist/**"],
+  "exclude": [
+    "**/*.test.*",
+    "**/*.d.ts",
+    "**/test/**",
+    "**/testing/**",
+    "packages/pg-protocol/src/b.ts",
+    "packages/pg-esm-test/**",
+    "packages/pg-bundler-test/**"
+  ],
+  "reporter": ["text", "lcov"]
+}
diff --git a/README.md b/README.md
index ecd94e792..2d7b3b5a1 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # node-postgres
 
 ![Build Status](https://github.com/brianc/node-postgres/actions/workflows/ci.yml/badge.svg)
+[![Coverage Status](https://coveralls.io/repos/github/brianc/node-postgres/badge.svg?branch=master)](https://coveralls.io/github/brianc/node-postgres?branch=master)
 <span class="badge-npmversion"><a href="https://npmjs.org/package/pg" title="View this project on NPM"><img src="https://img.shields.io/npm/v/pg.svg" alt="NPM version" /></a></span>
 <span class="badge-npmdownloads"><a href="https://npmjs.org/package/pg" title="View this project on NPM"><img src="https://img.shields.io/npm/dm/pg.svg" alt="NPM downloads" /></a></span>
 
diff --git a/package.json b/package.json
index e30454007..59489327b 100644
--- a/package.json
+++ b/package.json
@@ -16,6 +16,8 @@
     "docs:build": "cd docs && yarn build",
     "docs:start": "cd docs && yarn dev",
     "pretest": "yarn build",
+    "precoverage": "yarn build",
+    "coverage": "nyc --silent lerna exec --concurrency 1 --ignore pg-connection-string -- yarn test && nyc --no-clean yarn workspace pg-connection-string mocha",
     "prepublish": "yarn build",
     "lint": "eslint --cache 'packages/**/*.{js,ts,tsx}'"
   },
@@ -29,6 +31,7 @@
     "eslint-config-prettier": "^10.1.2",
     "eslint-plugin-prettier": "^5.1.2",
     "lerna": "^3.19.0",
+    "nyc": "^15",
     "prettier": "3.0.3",
     "typescript": "^6.0.3"
   },