diff --git a/workers/tagbackfillworker.py b/workers/tagbackfillworker.py
index 226a7f9dc..fa5f5b8d0 100644
--- a/workers/tagbackfillworker.py
+++ b/workers/tagbackfillworker.py
@@ -181,9 +181,9 @@ def backfill_tag(repositorytag):
     return False
 
   lifetime_start_ms = (repositorytag.lifetime_start_ts * 1000
-                       if repositorytag.lifetime_start_ts else None)
+                       if repositorytag.lifetime_start_ts is not None else None)
   lifetime_end_ms = (repositorytag.lifetime_end_ts * 1000
-                     if repositorytag.lifetime_end_ts else None)
+                     if repositorytag.lifetime_end_ts is not None else None)
 
   # Create the new Tag.
   with db_transaction():