diff --git a/pelican/plugins/activitypub/activitypub.py b/pelican/plugins/activitypub/activitypub.py
index 01ed1fb..ea76717 100644
--- a/pelican/plugins/activitypub/activitypub.py
+++ b/pelican/plugins/activitypub/activitypub.py
@@ -106,7 +106,7 @@ def ap_article(generator: pelican.ArticlesGenerator, writer: pelican.writers.Wri
         path = os.path.join(writer.output_path, 'activitypub/tags', t.slug)
         articles = []
         for article in generator.articles:
-            if t.name not in article.metadata['tags']:
+            if t.name not in article.metadata.get('tags', []):
                 continue
             articles.append(
                 os.path.join(generator.settings['SITEURL'], 'activitypub/posts', article.slug)