diff -r b78eccad3939 -r 1f3815703436 lib/Tools/java
--- a/lib/Tools/java	Thu Sep 12 18:53:51 2013 +0200
+++ b/lib/Tools/java	Thu Sep 12 20:53:25 2013 +0200
@@ -6,6 +6,9 @@
 
 declare -a JAVA_ARGS; eval "JAVA_ARGS=($ISABELLE_JAVA_SYSTEM_OPTIONS)"
 
+[ -n "$CLASSPATH" ] && classpath "$CLASSPATH"
+unset CLASSPATH
+
 isabelle_jdk java "${JAVA_ARGS[@]}" \
   -classpath "$(jvmpath "$ISABELLE_CLASSPATH")" "$@"