diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 4bd94e9..4be768e 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -69,6 +69,14 @@ jobs:
           else
             npm install --no-audit --no-fund
           fi
+      - name: Lockfile version matches package.json
+        # `npm ci` above already fails when the lockfile's DEPENDENCY entries
+        # disagree with package.json; it does not check the lockfile's copy of
+        # this project's own version. A release that bumps package.json without
+        # running an install leaves that field behind, and nothing caught it —
+        # measured in bareguard, stale across three consecutive releases.
+        # No-ops via --if-present in a repo that has not added the script.
+        run: npm run check:lockfile --if-present
       - name: Typecheck
         run: npm run typecheck --if-present
       - name: Test
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 77df17c..2a4154f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## [Unreleased]
+
+### Fixed
+
+- **The publish workflow now fails when `package-lock.json`'s version drifts from `package.json`.** npm writes that field on install, so a release that bumps `package.json` without running one leaves it behind — and nothing caught it: `npm ci` fails when the lockfile's *dependency* entries disagree, but never checks the lockfile's copy of the project's own version. `scripts/check-lockfile.mjs` (`npm run check:lockfile`) compares both places npm writes it and runs in the publish workflow. No lockfile is not a failure.
+
 ## 0.11.2 — 2026-08-31
 
 ### Added
diff --git a/package.json b/package.json
index 558cc21..6ee2d6b 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,8 @@
     "prepublishOnly": "npm run build:types",
     "test": "node --test test/unit/*.test.js test/integration/*.test.js",
     "test:ios": "node --test test/ios/*.test.js",
-    "ios:check": "node test/ios/check-prerequisites.js"
+    "ios:check": "node test/ios/check-prerequisites.js",
+    "check:lockfile": "node scripts/check-lockfile.mjs"
   },
   "keywords": [
     "android",
diff --git a/scripts/check-lockfile.mjs b/scripts/check-lockfile.mjs
new file mode 100644
index 0000000..6c7da1b
--- /dev/null
+++ b/scripts/check-lockfile.mjs
@@ -0,0 +1,53 @@
+// Fail when package-lock.json's copy of this project's own version disagrees
+// with package.json.
+//
+// npm writes that copy on install. A release that bumps package.json without
+// running an install leaves it behind, and nothing else catches it: `npm ci`
+// fails when the lockfile's DEPENDENCY entries disagree with package.json, but
+// it does not check the lockfile's copy of the project's own version. Measured
+// in bareguard, where it sat at 0.13.0 while 0.14.0, 0.15.0 and 0.16.0 all
+// shipped.
+//
+// Harmless to consumers — npm does not include a library's lockfile in the
+// published tarball — so this is repo hygiene, not a user-visible bug. It is a
+// hard failure anyway because it is trivially fixable and can never be a false
+// positive: it compares two numbers this repo owns.
+//
+// No lockfile is not a failure. Some repos deliberately ship without one, and
+// this check runs from a workflow shared across all of them.
+import { readFileSync } from "node:fs";
+import path from "node:path";
+
+const root = path.resolve(import.meta.dirname, "..");
+const read = (f) => JSON.parse(readFileSync(path.join(root, f), "utf8"));
+
+let lock;
+try {
+  lock = read("package-lock.json");
+} catch (err) {
+  if (err.code === "ENOENT") {
+    console.log("✓ no package-lock.json — nothing to check");
+    process.exit(0);
+  }
+  throw err;
+}
+
+const pkg = read("package.json");
+
+// Two places hold it: the lockfile root, and the root package's own entry in
+// `packages[""]`. npm writes both, so both are checked — drift in either is the
+// same drift, and checking only one lets the other move unseen.
+const found = {
+  "package-lock.json version": lock.version,
+  'package-lock.json packages[""].version': lock.packages?.[""]?.version,
+};
+const wrong = Object.entries(found).filter(([, v]) => v !== pkg.version);
+
+if (wrong.length) {
+  console.error(`✗ lockfile version drift — package.json is ${pkg.version}:`);
+  for (const [where, v] of wrong) console.error(`    ${where} = ${v ?? "(missing)"}`);
+  console.error("  Fix: npm install --package-lock-only   (then commit package-lock.json)");
+  process.exit(1);
+}
+
+console.log(`✓ package-lock.json version matches package.json — ${pkg.version}`);