diff --git a/javafx-ui-controls/src/javafx/scene/control/ComboBoxBase.java b/javafx-ui-controls/src/javafx/scene/control/ComboBoxBase.java
--- a/javafx-ui-controls/src/javafx/scene/control/ComboBoxBase.java
+++ b/javafx-ui-controls/src/javafx/scene/control/ComboBoxBase.java
@@ -81,14 +81,18 @@
      */
     public ObjectProperty<T> valueProperty() { return value; }
     private ObjectProperty<T> value = new SimpleObjectProperty<T>(this, "value") {
-        @Override public void set(T newValue) {
-            T oldValue = get();
-            super.set(newValue);
+        T oldValue;
+        
+        @Override protected void invalidated() {
+            super.invalidated();
+            T newValue = get();
             
             if ((oldValue == null && newValue != null) ||
                     oldValue != null && ! oldValue.equals(newValue)) {
                 fireEvent(new ActionEvent());
             }
+            
+            oldValue = newValue;
         }
     };
     public final void setValue(T value) { valueProperty().set(value); }