diff --git a/gcsfs/core.py b/gcsfs/core.py
index 6ae4c60c..7decb734 100644
--- a/gcsfs/core.py
+++ b/gcsfs/core.py
@@ -957,7 +957,7 @@ def created(self, path):
     def _parse_timestamp(self, timestamp):
         assert timestamp.endswith("Z")
         timestamp = timestamp[:-1]
-        timestamp = timestamp + "0" * (6 - len(timestamp.rsplit(".", 1)[1]))
+        timestamp = timestamp + "0" * (6 - len(timestamp.rsplit(".", 1)[-1]))
         return datetime.fromisoformat(timestamp + "+00:00")
 
     async def _info(self, path, generation=None, **kwargs):