diff --git a/.github/workflows/checks.yml b/.github/workflows/checks.yml
index 8a33f0ae..116a692b 100644
--- a/.github/workflows/checks.yml
+++ b/.github/workflows/checks.yml
@@ -35,7 +35,14 @@ jobs:
       - name: Build with Jekyll
         run: bundle exec jekyll build
         working-directory: ./docs
-      - name: Run HTML Proofer
-        run: bundle exec htmlproofer ./_site --disable-external --no-enforce-https
-        # --log-level :debug 
-        working-directory: ./docs
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+      - name: Run Lychee
+        uses: lycheeverse/lychee-action@v2
+        with:
+          args: >-
+            --offline --include-fragments
+            --fallback-extensions html
+            --index-files 'index.html,.'
+            --root-dir ${{ github.workspace }}/docs/_site
+            ./_site
+          workingDirectory: ./docs
+          fail: true
\ No newline at end of file
diff --git a/.github/workflows/jekyll-gh-pages.yml b/.github/workflows/jekyll-gh-pages.yml
index 93be48c4..d8cf45dc 100644
--- a/.github/workflows/jekyll-gh-pages.yml
+++ b/.github/workflows/jekyll-gh-pages.yml
@@ -49,10 +49,22 @@ jobs:
         env:
           JEKYLL_ENV: production
           PAGES_REPO_NWO: "${{ github.repository }}"
-      - name: Run HTML Proofer
-        run: bundle exec htmlproofer ./_site --disable-external --swap-urls "^${{ steps.pages.outputs.base_path }}/:/"
-        # --log-level :debug 
-        working-directory: ./docs
+      - name: Run Lychee
+        uses: lycheeverse/lychee-action@v2
+        with:
+          # --remap matches the fully-resolved file URI (not the raw href), so the pattern
+          # must include the file:// scheme and --root-dir prefix. The (/|$) tail handles
+          # both `/twinBASIC-docs/page` and bare `/twinBASIC-docs` — lychee strips trailing
+          # slashes before remap, so we can't require one in the pattern.
+          args: >-
+            --offline --include-fragments
+            --fallback-extensions html
+            --index-files 'index.html,.'
+            --remap '^file://${{ github.workspace }}/docs/_site${{ steps.pages.outputs.base_path }}(/|$) file://${{ github.workspace }}/docs/_site/'
+            --root-dir ${{ github.workspace }}/docs/_site
+            ./_site
+          workingDirectory: ./docs
+          fail: true
       - name: Upload artifact
         uses: actions/upload-pages-artifact@v5
         with:
diff --git a/docs/check.bat b/docs/check.bat
index 3c47b21e..76712b56 100644
--- a/docs/check.bat
+++ b/docs/check.bat
@@ -1,2 +1,2 @@
-@rem Use htmlproofer to check the links in the site
-bundle exec htmlproofer ./_site --disable-external --no-enforce-https
+@rem Use lychee to check the links in the site
+@"%~dp0..\.claude\lychee.exe" --offline --include-fragments --fallback-extensions html --index-files "index.html,." --root-dir ".\_site" ".\_site" %*
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