diff --git a/aclocal.m4 b/aclocal.m4
index 99e6a04..66b8eac 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -134,3 +134,28 @@ if test [$2] -ne 0; then
 else
 [$5]
 fi)])
+
+dnl --------------------------------------------------------------------------
+dnl  PA_HEADER_DEFINES
+dnl
+dnl  PA_HEADER_DEFINES(headers, type, value)
+dnl --------------------------------------------------------------------------
+AC_DEFUN(PA_HEADER_DEFINES,
+[AC_MSG_CHECKING([for definition of $3])
+ AC_TRY_COMPILE([$1],
+[
+int main()
+{
+	$2 dummy = $3;
+	return 0;
+}
+],
+[
+ pa_header_define=`echo HAVE_$3_DEFINITION | tr '[a-z]' '[A-Z]'`
+ AC_DEFINE_UNQUOTED($pa_header_define)
+ AC_MSG_RESULT(yes)
+],
+[
+ AC_MSG_RESULT(no)
+])])
+
diff --git a/config.h.in b/config.h.in
index 7cd48c0..6a07b14 100644
--- a/config.h.in
+++ b/config.h.in
@@ -23,6 +23,7 @@
 #undef HAVE_SETREUID
 #undef HAVE_SETREGID
 #undef HAVE_SETSID
+#undef HAVE_IPPORT_TFTP_DEFINITION
 #undef HAVE_SYSEXITS_H
 #undef HAVE_STRINGS_H
 #undef HAVE_LIBGEN_H
diff --git a/configure.in b/configure.in
index e1e19b1..cb20df5 100644
--- a/configure.in
+++ b/configure.in
@@ -9,6 +9,19 @@ AC_PROG_CC
 AC_C_CONST
 AC_C_INLINE
 
+PA_ADD_CFLAGS(-Wall)
+PA_ADD_CFLAGS(-W)
+PA_ADD_CFLAGS(-Wpointer-arith)
+PA_ADD_CFLAGS(-Wbad-function-cast)
+PA_ADD_CFLAGS(-Wcast-equal)
+PA_ADD_CFLAGS(-Wstrict-prototypes)
+PA_ADD_CFLAGS(-Wmissing-prototypes)
+PA_ADD_CFLAGS(-Wmissing-declarations)
+PA_ADD_CFLAGS(-Wnested-externs)
+PA_ADD_CFLAGS(-Winline)
+PA_ADD_CFLAGS(-Wcast-align)
+PA_ADD_CFLAGS(-pipe)
+
 AC_CHECK_HEADERS(sysexits.h)
 AC_CHECK_HEADERS(strings.h)
 AC_CHECK_HEADERS(libgen.h)
@@ -26,6 +39,8 @@ AC_CHECK_FUNCS(setregid)
 PA_MSGHDR_MSG_CONTROL
 PA_STRUCT_IN_PKTINFO
 
+PA_HEADER_DEFINES([#include <netinet/in.h>], int, IPPORT_TFTP)
+
 PA_WITH_BOOL(tcpwrappers, 1,
 [ --without-tcpwrappers	Disable tcpwrapper permissions checking],
 [
@@ -46,19 +61,6 @@ PA_WITH_BOOL(remap, 1,
 	])
 ],:)
 
-PA_ADD_CFLAGS(-Wall)
-PA_ADD_CFLAGS(-W)
-PA_ADD_CFLAGS(-Wpointer-arith)
-PA_ADD_CFLAGS(-Wbad-function-cast)
-PA_ADD_CFLAGS(-Wcast-equal)
-PA_ADD_CFLAGS(-Wstrict-prototypes)
-PA_ADD_CFLAGS(-Wmissing-prototypes)
-PA_ADD_CFLAGS(-Wmissing-declarations)
-PA_ADD_CFLAGS(-Wnested-externs)
-PA_ADD_CFLAGS(-Winline)
-PA_ADD_CFLAGS(-Wcast-align)
-PA_ADD_CFLAGS(-pipe)
-
 PA_SIGSETJMP([AC_DEFINE(HAVE_SIGSETJMP)])
 
 LIBXTRA=false
diff --git a/tftp/tftpsubs.h b/tftp/tftpsubs.h
index 0dff16e..5976235 100644
--- a/tftp/tftpsubs.h
+++ b/tftp/tftpsubs.h
@@ -51,6 +51,10 @@
 #include <setjmp.h>
 #include "../config.h"
 
+#ifndef HAVE_IPPORT_TFTP_DEFINITION
+#define IPPORT_TFTP	69
+#endif
+
 struct tftphdr;
 
 struct tftphdr *r_init(void);