diff --git a/exchange_calendars/exchange_calendar_xbue.py b/exchange_calendars/exchange_calendar_xbue.py
index 072af9e1..650c37e1 100644
--- a/exchange_calendars/exchange_calendar_xbue.py
+++ b/exchange_calendars/exchange_calendar_xbue.py
@@ -344,15 +344,16 @@ def adhoc_holidays(self):
             "2016-11-28",  # Day of National Sovereignty
         ]
 
-        return list(
-            chain(
+        return [
+            pd.Timestamp(d)
+            for d in chain(
                 misc_adhocs,
                 market_closures_2002_jan,
                 market_closures_2002_apr,
                 bridge_days,
                 irregular_observances,
             )
-        )
+        ]
 
     @property
     def special_closes(self):
diff --git a/exchange_calendars/exchange_calendar_xphs.py b/exchange_calendars/exchange_calendar_xphs.py
index 7c4c9a34..dba98d67 100644
--- a/exchange_calendars/exchange_calendar_xphs.py
+++ b/exchange_calendars/exchange_calendar_xphs.py
@@ -410,12 +410,13 @@ def adhoc_holidays(self):
             "2010-12-31",
         ]
 
-        return list(
-            chain(
+        return [
+            pd.Timestamp(d)
+            for d in chain(
                 misc_adhoc,
                 pre_2011_holidays,
                 ChineseNewYearAfter2011,
                 philippines_eid_al_adha,
                 philippines_eid_al_fitr,
             )
-        )
+        ]