diff --git a/SRC/configure.in b/SRC/configure.in
index b4be615..e69a2c0 100644
--- a/SRC/configure.in
+++ b/SRC/configure.in
@@ -116,6 +116,7 @@ AC_ARG_ENABLE(tos,
  [if test "$enableval" = "yes"; then
    if test $ac_have_tos = "yes"; then
      AC_DEFINE(HAVE_TOS)
+     TOS=1
    else
      AC_MSG_WARN([No TOS support on this system, request ignored])
    fi
@@ -123,6 +124,7 @@ AC_ARG_ENABLE(tos,
  dnl Default: enable it if supported
  if test $ac_have_tos = "yes"; then
    AC_DEFINE(HAVE_TOS)
+   TOS=1
  fi)
 
 if test "$GCC" = yes; then
@@ -148,6 +150,7 @@ DISPLAY_SETTING(ICP)
 DISPLAY_SETTING(OPENSSL)
 DISPLAY_SETTING(SMTP)
 DISPLAY_SETTING(TTCP)
+DISPLAY_SETTING(TOS)