diff --git a/prebuild.xml b/prebuild.xml
index 5003ae7661..d02f2b939f 100644
--- a/prebuild.xml
+++ b/prebuild.xml
@@ -126,6 +126,7 @@
 
       <ReferencePath>../../../../bin/</ReferencePath>
       <Reference name="System"/>
+      <Reference name="System.Core"/>
       <Reference name="System.Xml"/>
       <Reference name="System.Web"/>
       <Reference name="OpenSim.Framework"/>