I was running a toplevel make using GCJ 3.2.1: d `org.mozilla.javascript.LineBuffer.skipFormatChar()': ../../../rhug/rhino/upstream/src/org/mozilla/javascript/LineBuffer.java:455: Incompatible type for `&&'. Can't convert `int' to boolean. private static final boolean checkSelf = Context.check && true; ^ ../../../rhug/rhino/upstream/src/org/mozilla/javascript/LineBuffer.java:455: Incompatible type for `&&'. Can't convert `int' to boolean. private static final boolean checkSelf = Context.check && true; ^ 2 errors Attached a diff to fix it, the Context.check is defined as a final static boolean = true, so I hacked in (Context.check==true) which is correct to do as Context.check should be true at all times, it is unlikely that they will change this as they happily note that it is a Design by contract requirement.