diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 179eb24ea..dfeaf39dc 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,7 @@
+2015-11-02  Corinna Vinschen  <corinna@vinschen.de>
+
+	* include/netinet/ip.h (MAX_IPOPTLEN): Define.
+
 2015-11-02  Corinna Vinschen  <corinna@vinschen.de>
 
 	* sigproc.cc (class pending_signals): Drop sigproc_init friendship.
diff --git a/winsup/cygwin/include/netinet/ip.h b/winsup/cygwin/include/netinet/ip.h
index dd701512e..4d355423b 100644
--- a/winsup/cygwin/include/netinet/ip.h
+++ b/winsup/cygwin/include/netinet/ip.h
@@ -202,6 +202,8 @@ struct ip {
 #define IPOPT_OFFSET		2		/* offset within option */
 #define IPOPT_MINOFF		4		/* min value of above */
 
+#define MAX_IPOPTLEN           40
+
 /*
  * Time stamp option structure.
  */