Have got the rts stuff to compile by including .../ghc-5.04/HSlang.o on the compile command line. I think this means the linker is not including the object with defines Addr_Azh_con_info when it links the library (only objects actually referenced from an archive library get included in the final binary) however including the .o forces all the code in the library to be included. It looks like a problem with the arguments ghc passes to the linker, however passing -optl --undefined Addr_Azh_con_info (should force the linker to output the code containing the definiton) made no difference, so I'm a little confused by that. Keean Schupke Department of Electrical & Electronic Engineering, Imperial College.