diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/constraint/DateConstraint.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/constraint/DateConstraint.java
index 97cbeec50..86c87600b 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/constraint/DateConstraint.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/constraint/DateConstraint.java
@@ -34,6 +34,13 @@ public abstract class DateConstraint extends Constraint<Date> {
         return new BiggerOrEqualThan(date);
     }
 
+    public static Constraint<Date> equalTo(Date date) {
+        if (date == null) {
+            return Constraint.voidConstraint();
+        }
+        return new EqualTo(date);
+    }
+
     private long value;
 
     protected long getValue() {
@@ -62,6 +69,22 @@ public abstract class DateConstraint extends Constraint<Date> {
 
     protected abstract boolean isSatisfiedBy(Long time);
 
+    static final class EqualTo extends DateConstraint {
+        EqualTo(Date date) {
+            super(date);
+        }
+
+        @Override
+        protected long applyConstraintTo(Long time) {
+            return getValue();
+        }
+
+        @Override
+        protected boolean isSatisfiedBy(Long time) {
+            return getValue() == time;
+        }
+    }
+
     static class BiggerOrEqualThan extends DateConstraint {
 
         protected BiggerOrEqualThan(Date date) {
diff --git a/ganttzk/src/test/java/org/zkoss/ganttz/data/constraint/DateConstraintTest.java b/ganttzk/src/test/java/org/zkoss/ganttz/data/constraint/DateConstraintTest.java
index e22173b5e..644b88810 100644
--- a/ganttzk/src/test/java/org/zkoss/ganttz/data/constraint/DateConstraintTest.java
+++ b/ganttzk/src/test/java/org/zkoss/ganttz/data/constraint/DateConstraintTest.java
@@ -32,6 +32,7 @@ public class DateConstraintTest {
 
     private Constraint<Date> biggerOrEqualThanNow = DateConstraint
             .biggerOrEqualThan(now);
+    private Constraint<Date> equalToNow = DateConstraint.equalTo(now);
 
     @Test
     public void canCreateConstraintBiggerThan() {
@@ -53,4 +54,17 @@ public class DateConstraintTest {
                 .getTime())));
     }
 
+    @Test
+    public void canCreateConstraintEqualTo(){
+        assertThat(equalToNow.applyTo(new Date(now.getTime() + 1000)),
+                equalTo(now));
+    }
+
+    @Test
+    public void equalToNullLeaveValuesUnmodified() {
+        Constraint<Date> equalToNull = DateConstraint.equalTo(null);
+        Date value = new Date(now.getTime() + 1000);
+        assertThat(equalToNull.applyTo(value), equalTo(value));
+    }
+
 }