I've been trying for a little bit now to try to get this type of command line working: gsc -:d- -c -o <build directory>\<sub set build directory> ..\<some set of paths>\main.scm > out.txt And I end up with this error: *** ERROR IN ##main -- string expected for output: parameter What am I doing wrong? At least judging by the documentation, using the flags together should be supported. I've also tried many different permutation of the above command, just in case including: gsc -:d- -o <build directory>\<sub set build directory> -c ..\<some set of paths>\main.scm > out.txt gsc -:d- -o -c <build directory>\<sub set build directory> ..\<some set of paths>\main.scm > out.txt gsc -:d- -c <build directory>\<sub set build directory> ..\<some set of paths>\main.scm > out.txt Full story: I'm trying to get the gambit compiler working with the waf build system. Currently using this as the arguments to the build step: gsc -:d- -c -o ${TGT[0].bld_dir(env)} ${SRC} > out.txt Sadly, all I get is the above error. Any ideas? Thanks, Cameron