diff --git a/Makefile b/Makefile
index f213b4d..0740ac2 100644
--- a/Makefile
+++ b/Makefile
@@ -28,6 +28,7 @@ xpi: logos
 	@mkdir -p $(XPI_UNSIGNED_DIR) $(XPI_SIGNED_DIR)
 	@rm -f $(XPI_OUTPUT)
 	@cd webextension && zip -q -9 "../$(XPI_OUTPUT)" $(EXTENSION_FILES)
+	@python3 scripts/release/validate_xpi.py "$(XPI_OUTPUT)" webextension/manifest.json
 	@echo "Created $(XPI_OUTPUT)"
 
 check-tools:
diff --git a/XPI/signed/LinkLog-dummy.xpi b/XPI/signed/LinkLog-dummy.xpi
new file mode 100644
index 0000000..e3a1bd7
Binary files /dev/null and b/XPI/signed/LinkLog-dummy.xpi differ
diff --git a/XPI/unsigned/LinkLog-0.1.0.xpi b/XPI/unsigned/LinkLog-0.1.0.xpi
index f5e851f..e3a1bd7 100644
Binary files a/XPI/unsigned/LinkLog-0.1.0.xpi and b/XPI/unsigned/LinkLog-0.1.0.xpi differ
diff --git a/scripts/release/validate_release.py b/scripts/release/validate_release.py
index 12740c7..3faed8f 100644
--- a/scripts/release/validate_release.py
+++ b/scripts/release/validate_release.py
@@ -30,6 +30,11 @@ def main() -> None:
     if frontend_version != extension_version:
         fail(f'frontend version {frontend_version} does not match extension version {extension_version}')
 
+    gecko_settings = manifest.get('browser_specific_settings', {}).get('gecko', {})
+    data_permissions = gecko_settings.get('data_collection_permissions')
+    if data_permissions != {'required': ['websiteActivity'], 'optional': []}:
+        fail('Firefox data_collection_permissions must require websiteActivity and have no optional categories')
+
     settings = SETTINGS_PATH.read_text()
     match = re.search(r"version: str = os\.getenv\('LINKLOG_VERSION', '([^']+)'\)", settings)
     if not match:
@@ -52,7 +57,7 @@ def main() -> None:
             fail('signed XPI contains a corrupt member')
 
     updates = json.loads(UPDATES_PATH.read_text())
-    addon_id = manifest['browser_specific_settings']['gecko']['id']
+    addon_id = gecko_settings['id']
     update_entries = updates.get('addons', {}).get(addon_id, {}).get('updates', [])
     if not any(entry.get('version') == extension_version for entry in update_entries):
         fail(f'webextension/updates.json has no update entry for {extension_version}')
diff --git a/scripts/release/validate_xpi.py b/scripts/release/validate_xpi.py
new file mode 100644
index 0000000..1a87b51
--- /dev/null
+++ b/scripts/release/validate_xpi.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+"""Validate an unsigned LinkLog XPI produced by the Makefile."""
+
+import json
+import sys
+import zipfile
+from pathlib import Path
+
+
+REQUIRED_FILES = {
+    'manifest.json',
+    'logo.svg',
+    'icon-16.png',
+    'icon-32.png',
+    'icon-48.png',
+    'icon-96.png',
+    'options.css',
+    'options.html',
+    'options.js',
+    'popup.css',
+    'popup.html',
+    'popup.js',
+}
+
+
+def fail(message: str) -> None:
+    raise SystemExit(f'XPI validation failed: {message}')
+
+
+def main() -> None:
+    if len(sys.argv) != 3:
+        fail('usage: validate_xpi.py <xpi> <source-manifest>')
+
+    xpi_path = Path(sys.argv[1])
+    source_manifest_path = Path(sys.argv[2])
+    try:
+        source_manifest = json.loads(source_manifest_path.read_text())
+        with zipfile.ZipFile(xpi_path) as archive:
+            names = set(archive.namelist())
+            corrupt_member = archive.testzip()
+            if corrupt_member is not None:
+                fail(f'corrupt archive member: {corrupt_member}')
+            if 'manifest.json' not in names:
+                fail('manifest.json is missing')
+            packaged_manifest = json.loads(archive.read('manifest.json'))
+    except (OSError, zipfile.BadZipFile, json.JSONDecodeError) as error:
+        fail(str(error))
+
+    missing_files = REQUIRED_FILES - names
+    if missing_files:
+        fail(f'missing required files: {", ".join(sorted(missing_files))}')
+    unexpected_files = names - REQUIRED_FILES
+    if any(name.startswith('__MACOSX/') or name == '.DS_Store' for name in unexpected_files):
+        fail('archive contains macOS metadata')
+    if packaged_manifest != source_manifest:
+        fail('packaged manifest does not match webextension/manifest.json')
+
+    print(f'validated unsigned XPI {xpi_path}')
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file
diff --git a/webextension/manifest.json b/webextension/manifest.json
index dd3412a..52d6c9d 100644
--- a/webextension/manifest.json
+++ b/webextension/manifest.json
@@ -27,6 +27,10 @@
       "gecko": {
         "id": "linklog@kolkman.org",
         "strict_min_version": "109.0",
+        "data_collection_permissions": {
+          "required": ["websiteActivity"],
+          "optional": []
+        },
         "update_url": "https://git.kolkman.org/olaf/Link-Log/raw/branch/main/webextension/updates.json"
       }
   },