diff --git a/javafx-ui-controls/src/com/sun/javafx/scene/control/skin/ComboBoxListViewSkin.java b/javafx-ui-controls/src/com/sun/javafx/scene/control/skin/ComboBoxListViewSkin.java
--- a/javafx-ui-controls/src/com/sun/javafx/scene/control/skin/ComboBoxListViewSkin.java
+++ b/javafx-ui-controls/src/com/sun/javafx/scene/control/skin/ComboBoxListViewSkin.java
@@ -402,11 +402,12 @@
             }
         } else {
             int index = getIndexOfComboBoxValueInItemsList();
-            if (index > -1) {
-                buttonCell.setItem(null);
-                buttonCell.updateListView(listView);
-                buttonCell.updateIndex(index);
-            } else {
+            
+            buttonCell.setItem(null);
+            buttonCell.updateListView(listView);
+            buttonCell.updateIndex(index);
+                
+            if (index == -1) {
                 // RT-21336 Show the ComboBox value even though it doesn't
                 // exist in the ComboBox items list (part two of fix)
                 boolean empty = updateDisplayText(buttonCell, value, false);
diff --git a/javafx-ui-controls/src/javafx/scene/control/ComboBox.java b/javafx-ui-controls/src/javafx/scene/control/ComboBox.java
--- a/javafx-ui-controls/src/javafx/scene/control/ComboBox.java
+++ b/javafx-ui-controls/src/javafx/scene/control/ComboBox.java
@@ -403,6 +403,11 @@
                 // when we really should go into the updateValue(t1) call below.
                 // We should only ever go into this clause if t1 is null.
                 wasSetAllCalled = false;
+
+                // Fix for RT-26079 (this unfortunately breaks RT-22572 above)
+                if (getItems() == null || ! getItems().contains(t)) {
+                    updateValue(null);
+                }
             } else {
                 updateValue(t1);
             }
diff --git a/javafx-ui-controls/test/javafx/scene/control/ComboBoxTest.java b/javafx-ui-controls/test/javafx/scene/control/ComboBoxTest.java
--- a/javafx-ui-controls/test/javafx/scene/control/ComboBoxTest.java
+++ b/javafx-ui-controls/test/javafx/scene/control/ComboBoxTest.java
@@ -917,4 +917,33 @@
         assertEquals("2", buttonCell.getText());
         assertEquals(2, sm.getSelectedIndex());
     }
+    
+    @Test public void test_rt26079() {
+        SingleSelectionModel sm = comboBox.getSelectionModel();
+        
+        Stage stage = new Stage();
+        Scene scene = new Scene(comboBox);
+        stage.setScene(scene);
+        comboBox.impl_processCSS(true);
+        comboBox.show();
+        ListCell<String> buttonCell = (ListCell<String>) getDisplayNode();
+        
+        assertNull(sm.getSelectedItem());
+        assertNull(comboBox.getValue());
+        assertEquals("", buttonCell.getText());
+        assertEquals(-1, sm.getSelectedIndex());
+        
+        comboBox.getItems().setAll("0","1","2","3","4","5","6","7","8","9");
+        sm.selectFirst();
+        assertEquals("0", sm.getSelectedItem());
+        assertEquals("0", comboBox.getValue());
+        assertEquals("0", buttonCell.getText());
+        assertEquals(0, sm.getSelectedIndex());
+        
+        comboBox.getItems().setAll("10","11","12","13","14","15","16","17","18","19");
+        assertNull(sm.getSelectedItem());
+        assertNull("Actual value: " + comboBox.getValue(), comboBox.getValue());
+        assertEquals("", buttonCell.getText());
+        assertEquals(-1, sm.getSelectedIndex());
+    }
 }