3 files changed, 53 insertions, 0 deletions
diff --git a/src/quick/util/qquickbehavior.cpp b/src/quick/util/qquickbehavior.cpp
index 460e2ca554..d649f9ff97 100644
--- a/src/quick/util/qquickbehavior.cpp
+++ b/src/quick/util/qquickbehavior.cpp
@@ -201,6 +201,11 @@ void QQuickBehavior::write(const QVariant &value)
     // to the item, so we need to read the value after.
     const QVariant &currentValue = d->property.read();
 
+    if (d->targetValue == currentValue) {
+        QQmlPropertyPrivate::write(d->property, value, QQmlPropertyPrivate::BypassInterceptor | QQmlPropertyPrivate::DontRemoveBinding);
+        return;
+    }
+
     QQuickStateOperation::ActionList actions;
     QQuickStateAction action;
     action.property = d->property;
diff --git a/tests/auto/quick/qquickbehaviors/data/qtbug21549.qml b/tests/auto/quick/qquickbehaviors/data/qtbug21549.qml
new file mode 100644
index 0000000000..db076bca9a
--- /dev/null
+++ b/tests/auto/quick/qquickbehaviors/data/qtbug21549.qml
@@ -0,0 +1,18 @@
+import QtQuick 2.0
+
+Item {
+    width: 200
+    height: 200
+
+    property int behaviorCount: 0
+
+    Rectangle {
+        id: myRect
+        objectName: "myRect"
+        width: 100
+        height: 100
+        Behavior on x {
+            ScriptAction { script: ++behaviorCount }
+        }
+    }
+}
diff --git a/tests/auto/quick/qquickbehaviors/tst_qquickbehaviors.cpp b/tests/auto/quick/qquickbehaviors/tst_qquickbehaviors.cpp
index c40abbd55f..8ec76c94e9 100644
--- a/tests/auto/quick/qquickbehaviors/tst_qquickbehaviors.cpp
+++ b/tests/auto/quick/qquickbehaviors/tst_qquickbehaviors.cpp
@@ -81,6 +81,7 @@ private slots:
     void delayedRegistration();
     void startOnCompleted();
     void multipleChangesToValueType();
+    void currentValue();
 };
 
 void tst_qquickbehaviors::simpleBehavior()
@@ -495,6 +496,35 @@ void tst_qquickbehaviors::multipleChangesToValueType()
     QTRY_COMPARE(text->property("font").value<QFont>(), value);
 }
 
+//QTBUG-21549
+void tst_qquickbehaviors::currentValue()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, testFileUrl("qtbug21549.qml"));
+    QQuickItem *item = qobject_cast<QQuickItem*>(c.create());
+    QVERIFY(item);
+
+    QQuickRectangle *target = item->findChild<QQuickRectangle*>("myRect");
+    QVERIFY(target);
+
+    QCOMPARE(target->x(), qreal(0));
+
+    target->setProperty("x", 50);
+    QCOMPARE(item->property("behaviorCount").toInt(), 1);
+    QCOMPARE(target->x(), qreal(50));
+
+    target->setProperty("x", 50);
+    QCOMPARE(item->property("behaviorCount").toInt(), 1);
+    QCOMPARE(target->x(), qreal(50));
+
+    target->setX(100);
+    target->setProperty("x", 100);
+    QCOMPARE(item->property("behaviorCount").toInt(), 1);
+    QCOMPARE(target->x(), qreal(100));
+
+    delete item;
+}
+
 QTEST_MAIN(tst_qquickbehaviors)
 
 #include "tst_qquickbehaviors.moc"