diff --git a/src/deepgram/core/datetime_utils.py b/src/deepgram/core/datetime_utils.py
index 7c9864a9..c1923153 100644
--- a/src/deepgram/core/datetime_utils.py
+++ b/src/deepgram/core/datetime_utils.py
@@ -23,6 +23,8 @@ def _serialize_zoned_datetime(v: dt.datetime) -> str:
     if v.tzinfo is not None:
         return _serialize_zoned_datetime(v)
     else:
-        local_tz = dt.datetime.now().astimezone().tzinfo
+        if not hasattr(serialize_datetime, "_local_tz"):
+            serialize_datetime._local_tz = dt.datetime.now().astimezone().tzinfo
+        local_tz = serialize_datetime._local_tz
         localized_dt = v.replace(tzinfo=local_tz)
         return _serialize_zoned_datetime(localized_dt)