diff --git a/similarities/similarities_helper.py b/similarities/similarities_helper.py
index 47c2664..0050c1d 100644
--- a/similarities/similarities_helper.py
+++ b/similarities/similarities_helper.py
@@ -16,6 +16,7 @@ import pathlib
 from datetime import datetime
 from pathlib import Path
 import pickle
+import pytz
 
 class tf_weight(Enum):
     MaxTF = 1
@@ -186,7 +187,7 @@ def write_weekly_similarities(path, sims, week, names):
         
     # reformat as a pairwise list
     sims = sims.melt(id_vars=['_subreddit','week'],value_vars=names.subreddit.values)
-    sims.to_parquet(p / week)
+    sims.to_parquet(p / week.item().replace(tzinfo=pytz.UTC).isoformat('T'))
 
 def column_overlaps(mat):
     non_zeros = (mat != 0).astype('double')