diff --git a/build.xml b/build.xml
index 689439e08..a420ad5f4 100644
--- a/build.xml
+++ b/build.xml
@@ -92,6 +92,7 @@
   <target name="dist" depends="prepare,compile">
     <!-- build our various jar files -->
     <jar destfile="${deploy.dir}/${app.name}-base.jar">
+      <fileset dir="${classes.dir}" includes="com/threerings/io/**"/>
       <fileset dir="${classes.dir}" includes="com/threerings/util/**"/>
       <fileset dir="${classes.dir}" includes="com/threerings/resource/**"/>
       <fileset dir="${classes.dir}" includes="com/threerings/tools/**"/>