diff --git a/lib/lwres/include/lwres/lwres.h b/lib/lwres/include/lwres/lwres.h
index 203af58847..f92963adf5 100644
--- a/lib/lwres/include/lwres/lwres.h
+++ b/lib/lwres/include/lwres/lwres.h
@@ -167,6 +167,8 @@ typedef struct {
 #define LWRES_ADDRTYPE_V4		0x00000001U	/* ipv4 */
 #define LWRES_ADDRTYPE_V6		0x00000002U	/* ipv6 */
 
+#define LWRES_MAX_ALIASES		16		/* max # of aliases */
+
 ISC_LANG_BEGINDECLS
 
 int