The two packages don't "go together" per se. From what I understand, rkward just need to be compiled against the system version of R-base. If I understand the comments correctly, I think what triggered the bug what that the Leap version 0.6.3 had trouble compiling against the updated R-base version, hence a need for an update to 0.6.5? Well done for the reactivity on that bug, guys, by the way!!