Jay parser generator on Mac producing Java instead of C#

Question

I'm trying to run the Jay parser generator (using jar file). I'm running it like this:

Java -jar Jay.jar -cv < ./../jay/skeleton.cs parser.jay > jay-tmp.out && mv jay-tmp.out parser.cs

which works fine on my windows machine. However when running it on my Mac OSX machine I keep getting a Java source file instead of the requested C# source file. Any ideas on how to fix this?