diff --git a/lib/sockopt.h b/lib/sockopt.h
index 63e915d..bec2616 100644
--- a/lib/sockopt.h
+++ b/lib/sockopt.h
@@ -71,7 +71,7 @@
 #define SOPT_SIZE_CMSG_IFINDEX_IPV4() SOPT_SIZE_CMSG_PKTINFO_IPV4()
 #elif defined (SOPT_SIZE_CMSG_RECVIF_IPV4)
 #define SOPT_SIZE_CMSG_IFINDEX_IPV4() SOPT_SIZE_CMSG_RECVIF_IPV4()
-#elif /* Nothing available */
+#else /* Nothing available */
 #define SOPT_SIZE_CMSG_IFINDEX_IPV4() (sizeof (char *))
 #endif /* SOPT_SIZE_CMSG_IFINDEX_IPV4 */