diff --git a/libc/include/net/if.h b/libc/include/net/if.h
index f36f37e..0efbf7f 100644
--- a/libc/include/net/if.h
+++ b/libc/include/net/if.h
@@ -26,9 +26,13 @@
  * SUCH DAMAGE.
  */
 
+#ifndef _NET_IF_H_
+#define _NET_IF_H_
+
 #include <sys/socket.h>
 #include <linux/if.h>
 #include <sys/cdefs.h>
+
 #ifndef IF_NAMESIZE
 #define IF_NAMESIZE IFNAMSIZ
 #endif
@@ -42,3 +46,5 @@
 extern char*        if_indextoname(unsigned ifindex, char *ifname);
 
 __END_DECLS
+
+#endif