diff --git a/MBS.Framework/Drawing/Measurement.cs b/MBS.Framework/Drawing/Measurement.cs
index ab0747c..251c76b 100644
--- a/MBS.Framework/Drawing/Measurement.cs
+++ b/MBS.Framework/Drawing/Measurement.cs
@@ -77,6 +77,8 @@ namespace MBS.Framework.Drawing
 
 		static Measurement()
 		{
+			RegisterMeasurementUnit(MeasurementUnit.Unspecified, String.Empty);
+
 			RegisterMeasurementUnit(MeasurementUnit.Cm, "cm");
 			RegisterMeasurementUnit(MeasurementUnit.Em, "em");
 			RegisterMeasurementUnit(MeasurementUnit.Ex, "ex");
diff --git a/MBS.Framework/Drawing/MeasurementUnit.cs b/MBS.Framework/Drawing/MeasurementUnit.cs
index 6f24a9d..355857b 100644
--- a/MBS.Framework/Drawing/MeasurementUnit.cs
+++ b/MBS.Framework/Drawing/MeasurementUnit.cs
@@ -26,6 +26,8 @@ namespace MBS.Framework.Drawing
 	/// </summary>
 	public enum MeasurementUnit
 	{
+		Unspecified = 0,
+
 		/// <summary>Measurement is in pixels.</summary>
 		Pixel = 1,
 		/// <summary>Measurement is in points. A point represents 1/72 of an inch.</summary>