diff --git a/nikola/plugins/task/archive.py b/nikola/plugins/task/archive.py
index d32dcda91a..126aed4866 100644
--- a/nikola/plugins/task/archive.py
+++ b/nikola/plugins/task/archive.py
@@ -67,7 +67,7 @@ def _prepare_task(self, kw, name, lang, posts, items, template_name,
         if posts is not None:
             context["posts"] = posts
             # Depend on all post metadata because it can be used in templates (Issue #1931)
-            task_cfg.append(repr(p) for p in posts)
+            task_cfg.append([repr(p) for p in posts])
         else:
             # Depend on the content of items, to rebuild if links change (Issue #1931)
             context["items"] = items