On Windows NT, nt/config.h no longer defines CLASH_DETECTION, since NT does not support symbolic links, which are the bread and butter of CLASH_DETECTION today. However, src\filelock.c causes the build to fail because of this: #ifndef CLASH_DETECTION #error CLASH_DETECTION is not defined?? #endif How about this patch? 1998-12-11 Adrian Aichner <aichner(a)ecf.teradyne.com&gt; * filelock.c: It is not an error under native WINDOWSNT for CLASH_DETECTION to be undefined, since NT does not support symbolic links.