Primitive function arguments cause VerifyError

The following code:

def foo(double x, y) {
println "x: "+x
println "y: "+y
}

foo(10.0d, 0)

causes Groovy to complain that the value passed to y is the wrong type. Making foo a member function of a class (in another file), and giving it three arguments, the function runs but y is null and the value that should go to y, goes to the third arg. At one point I had it triggering an internal error in the JVM.

Changing double to Double fixes the problem.