diff --git a/include/netinet/tcp.h b/include/netinet/tcp.h
index f2f88b58616e8c8339f12ca863796d85d578219b..b7828a502dafe96e309566f80110fe9547a2cd3c 100644
--- a/include/netinet/tcp.h
+++ b/include/netinet/tcp.h
@@ -17,7 +17,6 @@
 #define	TCP_QUICKACK	 12
 #define TCP_CONGESTION	 13
 #define TCP_MD5SIG	 14
-#define TCP_COOKIE_TRANSACTIONS 15
 #define TCP_THIN_LINEAR_TIMEOUTS 16
 #define TCP_THIN_DUPACK  17
 #define TCP_USER_TIMEOUT 18