diff --git a/similarities/weekly_cosine_similarities.py b/similarities/weekly_cosine_similarities.py
index 1476b77..2b4b989 100755
--- a/similarities/weekly_cosine_similarities.py
+++ b/similarities/weekly_cosine_similarities.py
@@ -40,7 +40,7 @@ def _week_similarities(week, simfunc, tfidf_path, term_colname, included_subredd
                          term_colname=term_colname,
                          included_subreddits=included_subreddits,
                          topN=topN,
-                         week=week,
+                         week=week.item().replace(tzinfo=pytz.UTC).isoformat('T'),
                          rescale_idf=False)
     
     tfidf_colname='tf_idf'