diff --git a/projects/viztool/build.xml b/projects/viztool/build.xml
index 510c5d3e..9ac67a7d 100644
--- a/projects/viztool/build.xml
+++ b/projects/viztool/build.xml
@@ -15,12 +15,23 @@
   <property name="dist.jar"    value="${app.name}.jar"/>
   <property name="javadoc.dir" value="${deploy.dir}/docs"/>
 
-  <!-- declare our classpath -->
-  <path id="classpath">
+  <!-- declare our classpath business -->
+  <path id="base.classpath">
     <pathelement location="${deploy.dir}/classes"/>
     <fileset dir="lib" includes="**/*.jar"/>
-    <fileset dir="${java.libraries}" includes="**/*.jar"/>
   </path>
+  <path id="classpath">
+    <path refid="base.classpath"/>
+  </path>
+
+  <!-- include JAVA_LIBS jars in our classpath if it exists -->
+  <target name="check-java-libs" if="env.JAVA_LIBS">
+    <!-- overwrite the classpath with one that contains JAVA_LIBS jars -->
+    <path id="classpath">
+      <path refid="base.classpath"/>
+      <fileset dir="${env.JAVA_LIBS}" includes="**/*.jar"/>
+    </path>
+  </target>
 
   <!-- prepares the application directories -->
   <target name="prepare">