diff --git a/Assets/Fungus/Narrative/Editor/MenuTimerEditor.cs b/Assets/Fungus/Narrative/Editor/MenuTimerEditor.cs
index 4c94911f..666c55aa 100644
--- a/Assets/Fungus/Narrative/Editor/MenuTimerEditor.cs
+++ b/Assets/Fungus/Narrative/Editor/MenuTimerEditor.cs
@@ -17,7 +17,7 @@ namespace Fungus
 			if (NullTargetCheck()) // Check for an orphaned editor instance
 				return;
 
-			durationProp = serializedObject.FindProperty("duration");
+			durationProp = serializedObject.FindProperty("_duration");
 			targetBlockProp = serializedObject.FindProperty("targetBlock");
 		}
 		
diff --git a/Assets/Fungus/Narrative/Scripts/Commands/MenuTimer.cs b/Assets/Fungus/Narrative/Scripts/Commands/MenuTimer.cs
index dbee1b84..09066563 100644
--- a/Assets/Fungus/Narrative/Scripts/Commands/MenuTimer.cs
+++ b/Assets/Fungus/Narrative/Scripts/Commands/MenuTimer.cs
@@ -11,10 +11,14 @@ namespace Fungus
 	             "Menu Timer", 
 	             "Displays a timer bar and executes a target block if the player fails to select a menu option in time.")]
 	[AddComponentMenu("")]
-	public class MenuTimer : Command 
+	public class MenuTimer : Command, ISerializationCallbackReceiver 
 	{		
+		#region Obsolete Properties
+		[HideInInspector] [FormerlySerializedAs("duration")] public float durationOLD;
+		#endregion
+
 		[Tooltip("Length of time to display the timer for")]
-		public float duration;
+		public FloatData _duration = new FloatData(1);
 
 		[FormerlySerializedAs("targetSequence")]
 		[Tooltip("Block to execute when the timer expires")]
@@ -27,7 +31,7 @@ namespace Fungus
 			if (menuDialog != null &&
 			    targetBlock != null)
 			{
-				menuDialog.ShowTimer(duration, targetBlock);
+				menuDialog.ShowTimer(_duration.Value, targetBlock);
 			}
 
 			Continue();
@@ -55,6 +59,22 @@ namespace Fungus
 		{
 			return new Color32(184, 210, 235, 255);
 		}
+
+		//
+		// ISerializationCallbackReceiver implementation
+		//
+
+		public virtual void OnBeforeSerialize()
+		{}
+
+		public virtual void OnAfterDeserialize()
+		{
+			if (durationOLD != default(float))
+			{
+				_duration.Value = durationOLD;
+				durationOLD = default(float);
+			}
+		}
 	}
 
 }
\ No newline at end of file
diff --git a/Assets/UpdatePropTest.unity b/Assets/UpdatePropTest.unity
index ab3c9b74..e18423d2 100644
--- a/Assets/UpdatePropTest.unity
+++ b/Assets/UpdatePropTest.unity
@@ -311,6 +311,7 @@ GameObject:
   - 114: {fileID: 979963253}
   - 114: {fileID: 979963256}
   - 114: {fileID: 979963257}
+  - 114: {fileID: 979963258}
   m_Layer: 0
   m_Name: Flowchart
   m_TagString: Untagged
@@ -344,7 +345,7 @@ MonoBehaviour:
     height: 859
   selectedBlock: {fileID: 979963241}
   selectedCommands:
-  - {fileID: 979963257}
+  - {fileID: 979963258}
   variables:
   - {fileID: 979963244}
   - {fileID: 979963252}
@@ -416,6 +417,7 @@ MonoBehaviour:
   - {fileID: 979963253}
   - {fileID: 979963256}
   - {fileID: 979963257}
+  - {fileID: 979963258}
 --- !u!114 &979963242
 MonoBehaviour:
   m_ObjectHideFlags: 2
@@ -721,7 +723,26 @@ MonoBehaviour:
   itemId: 13
   errorMessage: 
   indentLevel: 0
-  duration: 5
+  durationOLD: 0
+  _duration:
+    floatRef: {fileID: 0}
+    floatVal: 5
+--- !u!114 &979963258
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_PrefabParentObject: {fileID: 0}
+  m_PrefabInternal: {fileID: 0}
+  m_GameObject: {fileID: 979963238}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: ab54728d981544842843ba6609b9a80a, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: 
+  itemId: 14
+  errorMessage: 
+  indentLevel: 0
+  duration: 6
+  targetBlock: {fileID: 979963241}
 --- !u!1 &1197120973
 GameObject:
   m_ObjectHideFlags: 0