diff --git a/prebuild.xml b/prebuild.xml
index b7350e0243..2af29f431d 100644
--- a/prebuild.xml
+++ b/prebuild.xml
@@ -465,6 +465,7 @@
       <ReferencePath>../../../bin/</ReferencePath>
       <Reference name="System" localCopy="false"/>
       <Reference name="System.Xml"/>
+      <Reference name="System.Drawing"/>
       <Reference name="libsecondlife.dll"/>
       <Reference name="Axiom.MathLib.dll"/>
       <Reference name="Db4objects.Db4o.dll"/>