diff --git a/test/syscalls/linux/socket_netlink_util.h b/test/syscalls/linux/socket_netlink_util.h
index da99f0d60..76e772c48 100644
--- a/test/syscalls/linux/socket_netlink_util.h
+++ b/test/syscalls/linux/socket_netlink_util.h
@@ -15,6 +15,8 @@
 #ifndef GVISOR_TEST_SYSCALLS_SOCKET_NETLINK_UTIL_H_
 #define GVISOR_TEST_SYSCALLS_SOCKET_NETLINK_UTIL_H_
 
+#include <sys/socket.h>
+// socket.h has to be included before if_arp.h.
 #include <linux/if_arp.h>
 #include <linux/netlink.h>