Explicitly use event timestamp when recording data in similarity index.
diff --git a/src/sentry/similarity.py b/src/sentry/similarity.py
index f59889b5174cb..65ad43ee14c11 100644
--- a/src/sentry/similarity.py
+++ b/src/sentry/similarity.py
@@ -12,6 +12,7 @@
 
 from sentry.utils import redis
 from sentry.utils.datastructures import BidirectionalMapping
+from sentry.utils.dates import to_timestamp
 from sentry.utils.iterators import shingle
 from sentry.utils.redis import load_script
 
@@ -299,6 +300,7 @@ def record(self, event):
             '{}'.format(event.project_id),
             '{}'.format(event.group_id),
             items,
+            timestamp=to_timestamp(event.datetime),
         )
 
     def query(self, group):
