diff --git a/.github/workflows/node.js.yml b/.github/workflows/node.js.yml
index 2be0a8e5..2fd1cb7c 100644
--- a/.github/workflows/node.js.yml
+++ b/.github/workflows/node.js.yml
@@ -27,6 +27,7 @@ jobs:
       run: echo "PUBLISH_PLEASE_DISABLE_PROMPT=true" >> $GITHUB_ENV
     - run: npm install --ignore-scripts
     - run: npm run test
+    - run: npm run test-types-nodenext
     - uses: coverallsapp/github-action@v1.1.1
       with:
         github-token: ${{ secrets.GITHUB_TOKEN }}
diff --git a/package.json b/package.json
index 23c4d1e5..7b2bf660 100644
--- a/package.json
+++ b/package.json
@@ -22,6 +22,7 @@
   "scripts": {
     "test": "c8 --reporter=lcov --reporter=text jasmine spec/*spec.js",
     "test-types": "tsc --noEmit spec/typings/typings-test.ts",
+    "test-types-nodenext": "tsc --noEmit -p spec/typings/tsconfig.nodenext.json",
     "unit": "jasmine",
     "coverage": "nyc report --reporter html --reporter text -t .nyc_output --report-dir .nyc_output/summary",
     "perf": "node ./benchmark/perfTest3.js",
diff --git a/spec/typings/nodenext-import-test.ts b/spec/typings/nodenext-import-test.ts
new file mode 100644
index 00000000..264bf762
--- /dev/null
+++ b/spec/typings/nodenext-import-test.ts
@@ -0,0 +1,10 @@
+/**
+ * Regression for GH-808: ESM declaration must use NodeNext-valid relative specifiers
+ * (e.g. `./pem.js` → resolves to `pem.d.ts`) so consumers with `moduleResolution: "NodeNext"`
+ * and `skipLibCheck: false` do not hit TS2834.
+ *
+ * Resolves the same entry as the package `import` types (`./src/fxp.d.ts`).
+ */
+import type { XMLParser } from "../../src/fxp.js";
+
+type _Smoke = XMLParser;
diff --git a/spec/typings/tsconfig.nodenext.json b/spec/typings/tsconfig.nodenext.json
new file mode 100644
index 00000000..d607e547
--- /dev/null
+++ b/spec/typings/tsconfig.nodenext.json
@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "strict": true,
+    "skipLibCheck": false,
+    "noEmit": true,
+    "types": []
+  },
+  "include": ["nodenext-import-test.ts"]
+}
diff --git a/src/fxp.d.ts b/src/fxp.d.ts
index 05e38de7..84199a16 100644
--- a/src/fxp.d.ts
+++ b/src/fxp.d.ts
@@ -1,4 +1,4 @@
-import type { Expression, ReadonlyMatcher } from './pem';
+import type { Expression, ReadonlyMatcher } from './pem.js';
 
 // jPath: true  → string
 // jPath: false → ReadonlyMatcher