diff --git a/build.xml b/build.xml
index 42c3009b4..d81db3041 100644
--- a/build.xml
+++ b/build.xml
@@ -352,7 +352,10 @@
     <property name="ignoresystemclasses" value="false"/>
     <available property="jdk1.5+" classname="java.net.Proxy"/>
     <available property="jdk1.6+" classname="java.util.ServiceLoader"/>
+    <available property="jdk1.7+" classname="java.nio.file.FileSystem"/>
     <available property="kaffe" classname="kaffe.util.NotImplemented"/>
+    <available property="harmony"
+               classname="org.apache.harmony.luni.util.Base64"/>
     <available property="bsf.present"
       classname="org.apache.bsf.BSFManager"
       classpathref="classpath" ignoresystemclasses="${ignoresystemclasses}"/>