diff --git a/external-worker/flowable/external_worker_client/utils.py b/external-worker/flowable/external_worker_client/utils.py
index 2646320..ad90680 100644
--- a/external-worker/flowable/external_worker_client/utils.py
+++ b/external-worker/flowable/external_worker_client/utils.py
@@ -1,4 +1,7 @@
 from datetime import datetime
 
 def parse_date_time(date):
-    return datetime.strptime(date, "%Y-%m-%dT%H:%M:%S.%fZ") if date is not None else None
+    try:
+        return datetime.strptime(date, "%Y-%m-%dT%H:%M:%S.%fZ") if date is not None else None
+    except ValueError:
+        return datetime.strptime(date, "%Y-%m-%dT%H:%M:%SZ") if date is not None else None
\ No newline at end of file
diff --git a/external-worker/tests/test_utils.py b/external-worker/tests/test_utils.py
new file mode 100644
index 0000000..b205684
--- /dev/null
+++ b/external-worker/tests/test_utils.py
@@ -0,0 +1,15 @@
+import datetime
+import unittest
+
+from flowable.external_worker_client.utils import parse_date_time
+
+
+class TestUtils(unittest.TestCase):
+
+    def test_parse_date_time_with_millis(self):
+        date = parse_date_time('2024-09-23T15:23:08.123Z')
+        self.assertEqual(datetime.datetime(2024, 9, 23, 15, 23, 8, 123000), date)
+
+    def test_parse_date_time_without_millis(self):
+        date = parse_date_time('2024-09-23T15:23:08Z')
+        self.assertEqual(datetime.datetime(2024, 9, 23, 15, 23, 8, 0), date)