diff --git a/src/gwt/build.xml b/src/gwt/build.xml
index 6581bd9..36eadc1 100644
--- a/src/gwt/build.xml
+++ b/src/gwt/build.xml
@@ -26,6 +26,7 @@
    <property name="gwt.main.module" value="org.rstudio.studio.RStudio"/>
    <property name="ace.bin" value="src/org/rstudio/studio/client/workbench/views/source/editors/text/ace"/>
    <property name="json2.bin" value="www/js"/>
+   <property environment="env"/>
 
    <path id="project.class.path">
       <pathelement location="bin"/>
@@ -102,6 +103,7 @@
          </classpath>
          <!-- add jvmarg -Xss16M or similar if you see a StackOverflowError -->
          <jvmarg value="-Xmx512M"/>
+         <jvmarg value="-Djava.util.prefs.userRoot=${env.T}"/>
          <arg value="-war"/>
          <arg value="www"/>
          <arg value="-localWorkers"/>