diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 9798deaac08..a6f46648d98 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -163,6 +163,7 @@ int shutdown( int, int );
 #include <netdb.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
+#include <netinet/tcp.h>
 
 /* Headers needed for inet_ntoa() and inet_addr() */
 #ifdef __BEOS__