diff --git a/18.md b/18.md
index 41c94424..7a8f810a 100644
--- a/18.md
+++ b/18.md
@@ -10,6 +10,7 @@ A repost is a `kind 6` event that is used to signal to followers
 that a `kind 1` text note is worth reading.
 
 The `content` of a repost event is _the stringified JSON of the reposted note_. It MAY also be empty, but that is not recommended.
+[NIP-70](70.md)-protected events SHOULD always have an empty `content`.
 
 The repost event MUST include an `e` tag with the `id` of the note that is
 being reposted. That tag MUST include a relay URL as its third entry
@@ -41,3 +42,4 @@ as a "generic repost", that can include any kind of event inside other than
 
 `kind 16` reposts SHOULD contain a `k` tag with the stringified kind number
 of the reposted event as its value.
+