Any ideas? If I don't import Yhc.Core, things appear to be working. The only thing suspicious is "scons build" died right after "scons: done building targets.": Copy("inst/lib/yhc/packages/haskell98/1.0/System.ycr", "src/packages/haskell98-1.0/System.ycr") scons: done building targets. Exception exceptions.TypeError: TypeError("'NoneType' object is not callable",) in <bound method Popen4.__del__ of <popen2.Popen4 instance at 0x8d0078c>> ignored This must be pilot error, because I get the same results on my Windows box. Thanks for any help! -Tom hawkit1@waterton:~/t1$ cat Main.hs module Main (main) where import Yhc.Core main :: IO () main = do putStrLn "hello Yhc.Core!" loadCore "Main.ycr" >>= print hawkit1@waterton:~/t1$ yhc --linkcore Main Error: File not found, Yhc.Core Reason: imported from Main Looked in: /home/hawkit1/t1/ /home/hawkit1/yhc/inst/lib/yhc/packages/haskell98/1.0 /home/hawkit1/yhc/inst/lib/yhc/packages/yhc-base/1.0 hawkit1@waterton:~/t1$