*** a/src/tools/msvc/build.pl
--- b/src/tools/msvc/build.pl
***************
*** 39,49 **** my $vcver = Mkvcbuild::mkvcbuild($config);
  
  my $bconf     = $ENV{CONFIG} || "Release";
  my $buildwhat = $ARGV[1]     || "";
! if ($ARGV[0] eq 'DEBUG')
  {
  	$bconf = "Debug";
  }
! elsif ($ARGV[0] ne "RELEASE")
  {
  	$buildwhat = $ARGV[0] || "";
  }
--- 39,49 ----
  
  my $bconf     = $ENV{CONFIG} || "Release";
  my $buildwhat = $ARGV[1]     || "";
! if (uc($ARGV[0]) eq 'DEBUG')
  {
  	$bconf = "Debug";
  }
! elsif (uc($ARGV[0]) ne "RELEASE")
  {
  	$buildwhat = $ARGV[0] || "";
  }