This problem can be solved by overriding the bootstrapclasspath. Just adding the path to the tools14.jar to the classpath argument is not enough because the com.sun.util.* get loaded before the class in the classpath. So you need to use the -Xbootclasspath/p: option which prepend archives (jar) or directory in front of the bootclasspath. But this is a non-standard option and according to the man file of java on MacOS X, "Applications that use this option for the purpose of overriding a class in the default bootstrap class path should not be deployed, as doing so would contravene the Java 2 Runtime Environment binary code license." So on the Mac OSX platform, you can edit <INSTALL-DIRECTORY>/D2KToolkit/D2KToolkit.app/Contents/Info.plist. Search for VMOptions and then add a line between the following array tag like "<string>-Xbootclasspath/p:/Applications/D2K/lib/tools14.jar</string>".