I'm trying to create a war file but I have this error:

bundle exec warble

warble aborted!
Error: Your application used more memory than the safety cap of 500m.
Specify -J-Xmx####m to increase it (#### = cap size in MB).
Specify -w for full OutOfMemoryError stack trace

Then I run

jruby -J-Xmx900m -S bundle exec warble

but I have the same problem.
How can I solve?

I'm using jruby-1.6.2 and rails 3.0.7.