diff --git a/dtool/src/attach/dtool.cshrc b/dtool/src/attach/dtool.cshrc
index 076e6a1f80..fbecea69c7 100644
--- a/dtool/src/attach/dtool.cshrc
+++ b/dtool/src/attach/dtool.cshrc
@@ -18,7 +18,7 @@ else if ( $OS == "IRIX64" ) then
              /usr/sbin /usr/bsd /sbin /usr/bin /bin /usr/bin/X11 /usr/etc  \
              /usr/demos/bin /usr/local/bin )
   setenv LD_LIBRARY_PATH "/usr/local/lib:."
-else if (($OS == "CYGWIN_NT-5.1") || ($OS == "CYGWIN_NT-6.0") || ($OS == "CYGWIN_NT-6.0-WOW64") || ($OS == "CYGWIN_NT-5.2-WOW64") || ($OS == "CYGWIN_NT-5.0") || ( $OS == "CYGWIN_NT-4.0" ) || ( $OS == "WINNT" )) then
+else if (($OS == "CYGWIN_NT-6.1-WOW64") || ($OS == "CYGWIN_NT-6.1") || ($OS == "CYGWIN_NT-5.1") || ($OS == "CYGWIN_NT-6.0") || ($OS == "CYGWIN_NT-6.0-WOW64") || ($OS == "CYGWIN_NT-5.2-WOW64") || ($OS == "CYGWIN_NT-5.0") || ( $OS == "CYGWIN_NT-4.0" ) || ( $OS == "WINNT" )) then
   set path = ( /bin /usr/bin /usr/lib /usr/local/bin $path . )
   if ( $?LIB ) then
     setenv LIB "$LIB;"`cygpath -w /usr/lib`