diff --git a/plusone-validator/src/main/java/xyz/zhouxy/plusone/validator/MapValidator.java b/plusone-validator/src/main/java/xyz/zhouxy/plusone/validator/MapValidator.java
index 2eda053..e724bf2 100644
--- a/plusone-validator/src/main/java/xyz/zhouxy/plusone/validator/MapValidator.java
+++ b/plusone-validator/src/main/java/xyz/zhouxy/plusone/validator/MapValidator.java
@@ -83,6 +83,12 @@ public abstract class MapValidator<K, V> extends BaseValidator<Map<K, V>> {
         return ruleForString(m -> (String) m.get(key));
     }
 
+    protected final <E extends Comparable<E>> ComparablePropertyValidator<Map<K, V>, E> ruleForComparable(K key) {
+        @SuppressWarnings("unchecked")
+        Function<Map<K, V>, E> getter = m -> (E) m.get(key);
+        return ruleForComparable(getter);
+    }
+
     protected final <E> CollectionPropertyValidator<Map<K, V>, E> ruleForCollection(K key) {
         @SuppressWarnings("unchecked")
         Function<Map<K, V>, Collection<E>> getter = m -> (Collection<E>) m.get(key);
diff --git a/plusone-validator/src/test/java/xyz/zhouxy/plusone/map/validator/MapValidatorTests.java b/plusone-validator/src/test/java/xyz/zhouxy/plusone/map/validator/MapValidatorTests.java
index 3cc7327..b2a2afe 100644
--- a/plusone-validator/src/test/java/xyz/zhouxy/plusone/map/validator/MapValidatorTests.java
+++ b/plusone-validator/src/test/java/xyz/zhouxy/plusone/map/validator/MapValidatorTests.java
@@ -1,3 +1,19 @@
+/*
+ * Copyright 2024-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package xyz.zhouxy.plusone.map.validator;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -102,7 +118,7 @@ class ParamsValidator extends MapValidator<String, Object> {
                 .notNull(d -> ExampleException.withMessage("The doubleProperty cannot be null, but it was %s", d));
         ruleForString(STRING_PROPERTY)
                 .notNull();
-        ruleFor(DATE_TIME_PROPERTY)
+        ruleForComparable(DATE_TIME_PROPERTY)
                 .notNull("The dateTimeProperty cannot be null");
         ruleFor(OBJECT_PROPERTY)
                 .notNull(() -> ExampleException.withMessage("The objectProperty cannot be null"));