Gisle Vanem made curl build fine on DOS (and MinGW) with djgpp, OpenSSL and his Watt-32 stack. 'make -f Makefile.dist djgpp' in the root curl dir should build it fine. Or enter 'lib' and do a 'make -f Makefile.dj clean all' to first delete 'lib/curl_config.h' which is possibly from a previous incompatible Windows-build. Note 1: djgpp 2.04 beta has a sscanf() bug so the URL parsing isn't done properly. Use djgpp 2.03 until they fix it. Note 2: Compile Watt-32 (and OpenSSL) with the same version of djgpp. Otherwise things go wrong because things like FS-extensions and errnos have been changed between releases. Note 3: Several 'USE_x' variables in 'common.dj' are on the 'USE_x ?= 0' form (conditional variable assignment). So one can build like this: c:\curl\lib> make -f makefile.dj USE_OPENSSL=1 USE_ZLIB=1 clean all