diff --git a/05.md b/05.md
index 7e823fba..57a39365 100644
--- a/05.md
+++ b/05.md
@@ -6,11 +6,11 @@ Mapping Nostr keys to DNS-based internet identifiers
 
 `final` `optional`
 
-On events of kind `0` (`user metadata`) one can specify the key `"nip05"` with an [internet identifier](https://datatracker.ietf.org/doc/html/rfc5322#section-3.4.1) (an email-like address) as the value. Although there is a link to a very liberal "internet identifier" specification above, NIP-05 assumes the `<local-part>` part will be restricted to the characters `a-z0-9-_.`, case-insensitive.
+On events of kind `0` (`user metadata`) one can specify the key `"nip05"` with an [internet identifier](https://datatracker.ietf.org/doc/html/rfc5322#section-3.4.1) (an email-like address) as the value. Although there is a link to a very liberal "internet identifier" specification above, the `<local-part>` part MUST only use characters `a-z0-9-_.`.
 
 Upon seeing that, the client splits the identifier into `<local-part>` and `<domain>` and use these values to make a GET request to `https://<domain>/.well-known/nostr.json?name=<local-part>`.
 
-The result should be a JSON document object with a key `"names"` that should then be a mapping of names to hex formatted public keys. If the public key for the given `<name>` matches the `pubkey` from the `user metadata` event, the client then concludes that the given pubkey can indeed be referenced by its identifier.
+The result should be a JSON document object with a key `"names"` that should then be a mapping of names to hex formatted public keys, in lowercase. If the public key for the given `<name>` matches the `pubkey` from the `user metadata` event, the client then concludes that the given pubkey can indeed be referenced by its identifier.
 
 ### Example
 
@@ -73,7 +73,7 @@ For example, if after finding that `bob@bob.com` has the public key `abc...def`,
 
 ### Public keys must be in hex format
 
-Keys must be returned in hex format. Keys in NIP-19 `npub` format are only meant to be used for display in client UIs, not in this NIP.
+Keys must be returned in hex format, in lowercase. Keys in NIP-19 `npub` format are only meant to be used for display in client UIs, not in this NIP.
 
 ### Showing just the domain as an identifier