diff --git a/exchange_calendars/calendar_helpers.py b/exchange_calendars/calendar_helpers.py
index ae6caec9..98991bad 100644
--- a/exchange_calendars/calendar_helpers.py
+++ b/exchange_calendars/calendar_helpers.py
@@ -12,7 +12,7 @@
 
 NANOSECONDS_PER_MINUTE = int(6e10)
 
-NP_NAT = np.array([pd.NaT], dtype=np.int64)[0]
+NP_NAT = pd.NaT.value
 
 Session = typing.Union[pd.Timestamp, str, int, float, datetime.datetime]