diff --git a/os-tcp-mtu.c b/os-tcp-mtu.c
index af39e99..0126f44 100644
--- a/os-tcp-mtu.c
+++ b/os-tcp-mtu.c
@@ -30,6 +30,7 @@
 /* For TCP_INFO */
 # include <linux/tcp.h>
 #endif
+#include <sys/sockio.h>
 
 union sa_ip46 {
 	struct sockaddr addr;