diff --git a/configure.in b/configure.in
index 06298750d..42589c2a4 100644
--- a/configure.in
+++ b/configure.in
@@ -865,7 +865,7 @@ AC_CHECK_FUNCS(backtrace)
 AC_CHECK_FUNCS(prctl)
 AC_CHECK_FUNCS(gethostbyname_r)
 
-AC_CHECK_HEADERS(net/pfkeyv2.h netipsec/ipsec.h netinet6/ipsec.h)
+AC_CHECK_HEADERS(net/pfkeyv2.h netipsec/ipsec.h netinet6/ipsec.h netinet/udp.h)
 
 AC_CHECK_MEMBERS([struct sockaddr.sa_len], [], [],
 [