diff --git a/cdds/cdds/qc/plugins/base/validators.py b/cdds/cdds/qc/plugins/base/validators.py
index 32142ebd7..8521c1b72 100644
--- a/cdds/cdds/qc/plugins/base/validators.py
+++ b/cdds/cdds/qc/plugins/base/validators.py
@@ -260,9 +260,12 @@ def date_validator(cls, template: str, calendar: str = '360_day') -> Callable[[A
         """
         def validator_function(value):
             try:
+                current_mode = Calendar.default().mode
                 Calendar.default().set_mode(calendar)
                 TimePointParser().strptime(value, template)
             except ValueError:
                 raise ValidationError("'{}' is not a valid date in a form of {}".format(value, template))
-
+            finally:
+                # revert to the cached mode
+                Calendar.default().set_mode(current_mode)
         return validator_function
diff --git a/cdds/cdds/tests/test_qc/plugins/base/test_validators.py b/cdds/cdds/tests/test_qc/plugins/base/test_validators.py
index 336c4c958..90b59abd1 100644
--- a/cdds/cdds/tests/test_qc/plugins/base/test_validators.py
+++ b/cdds/cdds/tests/test_qc/plugins/base/test_validators.py
@@ -3,6 +3,7 @@
 
 import unittest
 import numpy as np
+from metomi.isodatetime.data import Calendar
 from cdds.qc.plugins.base.validators import ControlledVocabularyValidator
 from cdds.qc.plugins.base.validators import ValidatorFactory, ValidationError
 from cdds.tests.test_qc.plugins.constants import CV_REPO
@@ -74,3 +75,12 @@ def test_date_validator(self):
         self.assertRaises(ValidationError, validator_gregorian, "2023-02-30T01:20:05Z")
         self.assertRaises(ValidationError, validator_360day, "2023-07-31T01:20:05Z")
         self.assertIsNone(validator_gregorian("2023-07-31T01:20:05Z"))
+
+    def test_date_validator_calendar_reset(self):
+        Calendar.default().set_mode("360_day")
+        validator_gregorian = ValidatorFactory.date_validator("%Y-%m-%dT%H:%M:%SZ", "gregorian")
+        self.assertIsNone(validator_gregorian("2023-07-31T01:20:05Z"))
+        self.assertEquals(Calendar.default().mode, "360_day")
+
+        self.assertRaises(ValidationError, validator_gregorian, "2023-02-30T01:20:05Z")
+        self.assertEquals(Calendar.default().mode, "360_day")