diff --git a/binderhub/events.py b/binderhub/events.py
index 02fa730e6..37a6ad957 100644
--- a/binderhub/events.py
+++ b/binderhub/events.py
@@ -4,7 +4,7 @@
 
 import json
 import logging
-from datetime import datetime
+import datetime
 
 import jsonschema
 from jupyterhub.traitlets import Callable
@@ -98,8 +98,9 @@ def emit(self, schema_name, version, event):
         schema = self.schemas[(schema_name, version)]
         jsonschema.validate(event, schema)
 
+        now_utc = datetime.datetime.now(tz=datetime.timezone.utc)
         capsule = {
-            "timestamp": datetime.utcnow().isoformat() + "Z",
+            "timestamp": now_utc.isoformat() + "Z",
             "schema": schema_name,
             "version": version,
         }