diff --git a/.github/htmltest-config.yml b/.github/htmltest-config.yml
new file mode 100644
index 0000000..982ee07
--- /dev/null
+++ b/.github/htmltest-config.yml
@@ -0,0 +1,14 @@
+CheckDoctype: false
+CheckLinks: false
+CheckMeta: false
+CheckGeneric: false
+CheckInternal: false
+CheckInternalHash: false
+CheckMailto: false
+CheckTel: false
+CheckMetaRefresh: false
+IgnoreInternalEmptyHash: true
+IgnoreEmptyHref: true
+IgnoreAltMissing: true
+IgnoreAltEmpty: true
+IgnoreDirectoryMissingTrailingSlash: true
diff --git a/.github/workflows/link-checker.yml b/.github/workflows/link-checker.yml
new file mode 100644
index 0000000..be0280e
--- /dev/null
+++ b/.github/workflows/link-checker.yml
@@ -0,0 +1,39 @@
+# Run htmltest to check for broken external links
+# Scheduled for every first wednesday of the month
+
+name: Check broken links (htmltest)
+on:
+  workflow_dispatch:
+    branches:
+      - develop
+  schedule:
+    - cron: '20 8 1-7 * 3'
+
+jobs:
+  htmltest:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v3
+        
+      - name: Set up Hugo
+        uses: peaceiris/actions-hugo@v2
+        with:
+          hugo-version: "latest"
+          
+      - name: Run Hugo
+        run: hugo -d dist
+      
+      - name: Test HTML
+        continue-on-error: true
+        uses: wjdp/htmltest-action@master
+        with:
+          path: dist
+          config: .github/htmltest-config.yml
+      
+      - name: Archive htmltest results
+        uses: actions/upload-artifact@v3
+        with:
+          name: htmltest-report
+          path: tmp/.htmltest/htmltest.log
+          retention-days: 7
diff --git a/layouts/collections/single.html b/layouts/collections/single.html
index 8c23f88..d15e22c 100644
--- a/layouts/collections/single.html
+++ b/layouts/collections/single.html
@@ -181,7 +181,7 @@ <h4>Sample information</h4>
           <div class="row ml-0">
             <div class="col-md-auto pl-0 font-weight-bold">Materials:</div>
             <div class="col-md pl-0">{{ range (.GetTerms "materials") }}
-              <span class="m-1 badge badge-blue taxonomy-term"><a href="{{ .Permalink }}">{{ .LinkTitle }}</a></span>
+              <span class="m-1 badge badge-blue taxonomy-term"><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></span>
               {{ end }}
             </div>
           </div>
@@ -236,4 +236,4 @@ <h5>Biobank contact information</h5>
   </div>
 </div>
 
-{{ end }}
\ No newline at end of file
+{{ end }}