diff --git a/configure.in b/configure.in
index 96d19f7..3836fb5 100644
--- a/configure.in
+++ b/configure.in
@@ -1,5 +1,5 @@
 AC_INIT(samplicate.c)
-AM_INIT_AUTOMAKE(samplicate, 1.3.5)
+AM_INIT_AUTOMAKE(samplicate, 1.3.6)
 AM_CONFIG_HEADER(config.h)
 AC_PROG_CC
 AC_PROG_INSTALL
@@ -9,4 +9,8 @@ AC_STDC_HEADERS
 AC_CHECK_HEADERS(stdlib.h unistd.h ctype.h arpa/inet.h netinet/in_systm.h sys/uio.h)
 AC_CHECK_FUNCS(memcpy strchr)
 AC_REPLACE_FUNCS(inet_aton)
+AC_DEFINE([HAVE_STRUCT_IP], 1,
+	  [Define if the system has `struct ip'.])
+AC_DEFINE([HAVE_STRUCT_IPHDR], 1,
+	  [Define if the system has `struct iphdr'.])
 AC_OUTPUT(Makefile)