diff --git a/config.h.in b/config.h.in
index 4cd770ac7a..0b97d4107f 100644
--- a/config.h.in
+++ b/config.h.in
@@ -110,6 +110,9 @@
 /* Define to enable rpz nsip rules. */
 #undef ENABLE_RPZ_NSIP
 
+/* define if you want TCP_FASTOPEN enabled if available */
+#undef ENABLE_TCP_FASTOPEN
+
 /* Solaris hack to get select_large_fdset. */
 #undef FD_SETSIZE
 
diff --git a/configure b/configure
index 81c249eda5..5525ff2dd0 100755
--- a/configure
+++ b/configure
@@ -715,7 +715,6 @@ DST_EXTRA_SRCS
 DST_EXTRA_OBJS
 USE_ISC_SPNEGO
 READLINE_LIB
-ISC_PLATFORM_HAVETFO
 BIND9_CO_RULE
 LIBTOOL_MODE_UNINSTALL
 LIBTOOL_MODE_LINK
@@ -1606,7 +1605,7 @@ Optional Features:
   --enable-backtrace      log stack backtrace on abort [default=yes]
   --enable-symtable       use internal symbol table for backtrace
                           [all|minimal(default)|none]
-  --disable-tcp-fastopen  disable TCP Fast Open support [default=autodetect]
+  --disable-tcp-fastopen  disable TCP Fast Open support [default=yes]
   --disable-isc-spnego    use SPNEGO from GSSAPI library
   --disable-chroot        disable chroot
   --disable-linux-caps    disable Linux capabilities
@@ -17512,45 +17511,16 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 # Check whether --enable-tcp_fastopen was given.
 if test "${enable_tcp_fastopen+set}" = set; then :
   enableval=$enable_tcp_fastopen;
-fi
-
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for TCP_FASTOPEN socket option" >&5
-$as_echo_n "checking for TCP_FASTOPEN socket option... " >&6; }
-case "$enable_tcp_fastopen" in
-yes|''|autodetect)
-	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/tcp.h>
-#ifdef TCP_FASTOPEN
-int has_tfo() { return (0); }
-#endif
-
-_ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "has_tfo" >/dev/null 2>&1; then :
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-		ISC_PLATFORM_HAVETFO="#define ISC_PLATFORM_HAVETFO 1"
 else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-		ISC_PLATFORM_HAVETFO="#undef ISC_PLATFORM_HAVETFO"
+  enable_tcp_fastopen="yes"
 fi
-rm -f conftest*
 
 
-		;;
-	no)
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: disabled" >&5
-$as_echo "disabled" >&6; }
-		ISC_PLATFORM_HAVETFO="#undef ISC_PLATFORM_HAVETFO"
-		;;
-esac
+if test "$enable_tcp_fastopen" = "yes"; then :
 
+$as_echo "#define ENABLE_TCP_FASTOPEN 1" >>confdefs.h
+
+fi
 
 #
 # Check for some other useful functions that are not ever-present.
diff --git a/configure.in b/configure.in
index 6b5825e78f..cc65682838 100644
--- a/configure.in
+++ b/configure.in
@@ -1816,33 +1816,13 @@ AC_COMPILE_IFELSE(
 # comment in lib/isc/unix/socket.c).
 #
 
-AC_ARG_ENABLE(tcp_fastopen,
-	      AS_HELP_STRING([--disable-tcp-fastopen],
-		     [disable TCP Fast Open support [default=autodetect]]))
+AC_ARG_ENABLE([tcp_fastopen],
+	      [AS_HELP_STRING([--disable-tcp-fastopen],
+			      [disable TCP Fast Open support [default=yes]])],
+	     [], [enable_tcp_fastopen="yes"])
 
-AC_MSG_CHECKING(for TCP_FASTOPEN socket option)
-case "$enable_tcp_fastopen" in
-yes|''|autodetect)
-	AC_EGREP_CPP(has_tfo, [
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/tcp.h>
-#ifdef TCP_FASTOPEN
-int has_tfo() { return (0); }
-#endif
-],
-		[AC_MSG_RESULT(yes)
-		ISC_PLATFORM_HAVETFO="#define ISC_PLATFORM_HAVETFO 1"],
-		[AC_MSG_RESULT(no)
-		ISC_PLATFORM_HAVETFO="#undef ISC_PLATFORM_HAVETFO"])
-
-		;;
-	no)
-		AC_MSG_RESULT(disabled)
-		ISC_PLATFORM_HAVETFO="#undef ISC_PLATFORM_HAVETFO"
-		;;
-esac
-AC_SUBST(ISC_PLATFORM_HAVETFO)
+AS_IF([test "$enable_tcp_fastopen" = "yes"],
+      [AC_DEFINE([ENABLE_TCP_FASTOPEN], [1], [define if you want TCP_FASTOPEN enabled if available])])
 
 #
 # Check for some other useful functions that are not ever-present.
diff --git a/lib/isc/include/isc/platform.h.in b/lib/isc/include/isc/platform.h.in
index 6552c01f80..689950146d 100644
--- a/lib/isc/include/isc/platform.h.in
+++ b/lib/isc/include/isc/platform.h.in
@@ -36,17 +36,6 @@
  *** Network.
  ***/
 
-/*! \brief
- * Define if the system has struct lifconf which is a extended struct ifconf
- * for IPv6.
- */
-@ISC_PLATFORM_HAVELIFCONF@
-
-/*! \brief
- * Define if the system has TCP_FASTOPEN socket option.
- */
-@ISC_PLATFORM_HAVETFO@
-
 /***
  *** Miscellaneous.
  ***/
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index d61827b16a..d8ecdcb3cb 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -85,7 +85,7 @@
 #include <sys/utsname.h>
 #endif
 
-#ifdef ISC_PLATFORM_HAVETFO
+#ifdef ENABLE_TCP_FASTOPEN
 #include <netinet/tcp.h>
 #endif
 
@@ -5464,7 +5464,7 @@ isc__socket_filter(isc_socket_t *sock0, const char *filter) {
  */
 static void
 set_tcp_fastopen(isc__socket_t *sock, unsigned int backlog) {
-#if defined(ISC_PLATFORM_HAVETFO) && defined(TCP_FASTOPEN)
+#if defined(ENABLE_TCP_FASTOPEN) && defined(TCP_FASTOPEN)
 	char strbuf[ISC_STRERRORSIZE];
 
 /*
diff --git a/lib/isc/win32/socket.c b/lib/isc/win32/socket.c
index 9add374881..b4b9e2d609 100644
--- a/lib/isc/win32/socket.c
+++ b/lib/isc/win32/socket.c
@@ -3318,7 +3318,7 @@ isc__socket_filter(isc_socket_t *sock, const char *filter) {
 isc_result_t
 isc__socket_listen(isc_socket_t *sock, unsigned int backlog) {
 	char strbuf[ISC_STRERRORSIZE];
-#if defined(ISC_PLATFORM_HAVETFO) && defined(TCP_FASTOPEN)
+#if defined(ENABLE_TCP_FASTOPEN) && defined(TCP_FASTOPEN)
 	char on = 1;
 #endif
 
@@ -3351,7 +3351,7 @@ isc__socket_listen(isc_socket_t *sock, unsigned int backlog) {
 		return (ISC_R_UNEXPECTED);
 	}
 
-#if defined(ISC_PLATFORM_HAVETFO) && defined(TCP_FASTOPEN)
+#if defined(ENABLE_TCP_FASTOPEN) && defined(TCP_FASTOPEN)
 	if (setsockopt(sock->fd, IPPROTO_TCP, TCP_FASTOPEN,
 		       &on, sizeof(on)) < 0) {
 		strerror_r(errno, strbuf, sizeof(strbuf));