Sorry, you cannot build this module on a non-Cygwin Perl, but am letting you proceed in case you are trying to build a release tarball or something. Checking if your kit is complete... Looks good Writing Makefile for Filesys::CygwinPaths cp lib/Filesys/CygwinPaths.pm blib/lib/Filesys/CygwinPaths.pm /Users/cpanrun/pristine/5.8.7/bin/perl /Users/cpanrun/pristine/5.8.7/lib/5.8.7/ExtUtils/xsubpp -typemap /Users/cpanrun/pristine/5.8.7/lib/5.8.7/ExtUtils/typemap -typemap Cygwin.typemap path_protocol.xs > path_protocol.xsc && mv path_protocol.xsc path_protocol.c Please specify prototyping behavior for path_protocol.xs (see perlxs manual) gcc -c -I. -fno-common -DPERL_DARWIN -no-cpp-precomp -arch ppc -arch i386 -nostdinc -B/Developer/SDKs/MacOSX10.4u.sdk/usr/include/gcc -B/Developer/SDKs/MacOSX10.4u.sdk/usr/lib/gcc -isystem/Developer/SDKs/MacOSX10.4u.sdk/usr/include -F/Developer/SDKs/MacOSX10.4u.sdk/System/Library/Frameworks -mmacosx-version-min=10.3 -DUSE_SITECUSTOMIZE -DNO_HASH_SEED -fno-strict-aliasing -pipe -O2 -Wundef -DVERSION=\"0.04\" -DXS_VERSION=\"0.04\" "-I/Users/cpanrun/pristine/5.8.7/lib/5.8.7/darwin-thread-multi-2level/CORE" path_protocol.c In file included from path_protocol.xs:5: path_protocol.h:8:24: error: sys/cygwin.h: No such file or directory In file included from path_protocol.xs:5: path_protocol.h:8:24: error: sys/cygwin.h: No such file or directory lipo: can't open input file: /var/tmp//cc8mEhuV.out (No such file or directory) make: *** [path_protocol.o] Error 1