iconv.c includes unistd.h, which is not available on Windows, but not needed at all as well, because iconv uses APR and its apr_getopt itself. The comment around unistd.h states that it was only needed for getopt. My current workaround, because I don't want to patch the source, is to provide an empty unistd.h file in the search paths for includes. So I propose to simply remove that line entirely. Thanks!