diff --git a/src/ndisc/nm-ndisc.h b/src/ndisc/nm-ndisc.h
index 8861a17be..34595b0dc 100644
--- a/src/ndisc/nm-ndisc.h
+++ b/src/ndisc/nm-ndisc.h
@@ -109,8 +109,8 @@ typedef enum {
 } NMNDiscConfigMap;
 
 #define NM_NDISC_MAX_ADDRESSES_DEFAULT 16
-#define NM_NDISC_ROUTER_SOLICITATIONS_DEFAULT 3
-#define NM_NDISC_ROUTER_SOLICITATION_INTERVAL_DEFAULT 4
+#define NM_NDISC_ROUTER_SOLICITATIONS_DEFAULT 3          /* RFC4861 MAX_RTR_SOLICITATIONS */
+#define NM_NDISC_ROUTER_SOLICITATION_INTERVAL_DEFAULT 4  /* RFC4861 RTR_SOLICITATION_INTERVAL */
 
 struct _NMNDiscPrivate;
 struct _NMNDiscDataInternal;