diff --git a/clatd.h b/clatd.h
index 3459b09..44a655e 100644
--- a/clatd.h
+++ b/clatd.h
@@ -18,6 +18,7 @@
 #ifndef __CLATD_H__
 #define __CLATD_H__
 
+#include <linux/if.h>
 #include <linux/if_tun.h>
 
 #define MAXMTU 1500
@@ -30,4 +31,9 @@
 // how frequently (in seconds) to poll for an address change while there is no traffic
 #define NO_TRAFFIC_INTERFACE_POLL_FREQUENCY 90
 
+struct tun_data {
+  char device6[IFNAMSIZ], device4[IFNAMSIZ];
+  int fd6, fd4;
+};
+
 #endif /* __CLATD_H__ */