diff --git a/prebuild.xml b/prebuild.xml
index c64f1cc79b..54f42f44f2 100644
--- a/prebuild.xml
+++ b/prebuild.xml
@@ -3292,6 +3292,7 @@
       <Reference name="OpenSim.Region.OptionalModules"/>
       <Reference name="OpenSim.Region.ScriptEngine.Shared"/>
       <Reference name="OpenSim.Region.ScriptEngine.XEngine"/>
+      <Reference name="OpenSim.Services.Interfaces"/>
       <Reference name="OpenSim.Services.AvatarService"/>
       <Reference name="OpenSim.Tests.Common"/>
       <Files>