Hi, In latest ASDF, the function #’sys:pid-exit-status is used for LispWorks 6 and early versions, but I found this symbol doesn’t have a bounded function at all: CL-USER 1 > (describe 'sys:pid-exit-status) SYSTEM:PID-EXIT-STATUS is a SYMBOL NAME "PID-EXIT-STATUS" VALUE #<unbound value> FUNCTION #<unbound function> PLIST NIL PACKAGE #<The SYSTEM package, 6625/8192 internal, 1277/2048 external> In LispWorks 7.0, it’s even not an external symbol. On the other side, the function #’sys:pipe-exit-status exists since at least LispWorks 5.1.2, I think it should be used for all LispWorks versions, not just 7. The function #’sys:pipe-pid used in another ASDF function, exists since LispWorks 6.1, but ASDF only use it for LispWorks after 7.0. I don’t know if this could cause any potential problem in LispWorks 6.1, but I guess there’s no problem calling it also in 6.1. Basically I don’t know the purpose of these function calls, no actually tests were done. Use the patch with cautions … just calling non-exist functions are definitely wrong. Regards, Chun Tian