diff --git a/INSTALL b/INSTALL
index 46d0619a9..0cb5ab992 100644
--- a/INSTALL
+++ b/INSTALL
@@ -1,6 +1,6 @@
 INSTALL NOTES
 
-1) Run the configure script, ie: "./configure".  See the SUPPORTED file
+0) Run the configure script, ie: "./configure".  See the SUPPORTED file
    for a list of OS's sudo is known to work on.  Configure will generate
    config.h, pathnames.h, Makefile and visudoers/Makefile.  You shouldn't
    need to hand-edit the Makefiles but if you don't like configure's choice
@@ -8,6 +8,11 @@ INSTALL NOTES
    use the --prefix flag to configure to install sudo/visudo in a place
    other than /usr/local (ie: --prefix=/opt).
 
+   NOTE: if you use C2 security you need to use the --with-C2 flag to
+   configure.  Currently this only affect hpux.  You can use --with-C2
+   if you are just expecting to migrate to C2 security later but it makes
+   password lookups about twice as slow.
+
 1) Read sudo.h to enable/disable the options you may or may not want.
 
 2) Type make.  If configure did its job correctly there won't be any