LzmaDecodeInno.obj is compiled using the Borland C++Builder 6 compiler ("Borland C++ 5.6.4 for Win32") as follows: bcc32 -c -pr -O2 -D_LZMA_OUT_READ -D_LZMA_IN_CB LzmaDecodeInno.c Add -v if you wish to enable source-level debugging, which makes it possible to step through the C code from within Delphi. -JR