diff -r 3d33847dc911 -r 982f0bf34804 bin/isabelle_java
--- a/bin/isabelle_java	Mon Jan 22 22:45:45 2018 +0100
+++ b/bin/isabelle_java	Tue Jan 23 16:37:57 2018 +0100
@@ -66,6 +66,8 @@
   else
     unset ISABELLE_HOME
     unset CLASSPATH
-    exec "$JAVA_HOME/bin/java" "${JAVA_ARGS[@]}" -classpath "$ISABELLE_CLASSPATH" "$@"
+    exec "$JAVA_HOME/bin/java" "${JAVA_ARGS[@]}" \
+      "-Djava.ext.dirs=$JAVA_HOME/lib/ext" \
+      -classpath "$ISABELLE_CLASSPATH" "$@"
   fi
 }