On line 100 static float minVar = 0.0; /* minimum variance (diagonal only) And on line 211 static float minVar; /* variance floor if vFloor not specified in hmm set. */ Because of that, trying to compile with visual studio result the fallow message error: HMMIRest.c(211) : error C2370: 'minVar' : redefinition; different storage class HMMIRest.c(100) : see declaration of 'minVar' To do this job, I comment the second definition on line 211. I also make a change of my tool to compile htk with visual studio (HTK34Compile.bat). It’s don’t stop if it’s fail to compile HMMIRest. This can be downloaded on www.co.it.pt/~aveiga/htk