diff --git a/57.md b/57.md
index bbeb629d..79f167c6 100644
--- a/57.md
+++ b/57.md
@@ -26,7 +26,7 @@ Having lightning receipts on nostr allows clients to display lightning payments
 
 1. Calculate the lnurl pay request url for a user from the lud06 or lud16 field on their profile
 
-2. Fetch the lnurl pay request static endpoint (`https://host.com/.well-known/lnurlp/user`) and gather the `allowsNostr` and `nostrPubkey` fields. If `allowsNostr` exists and it is `true`, and if `nostrPubkey` exists and is a valid BIP 340 public key, associate this information with the user. The `nostrPubkey` is the `zapper`'s pubkey, and it is used to authorize zaps sent to that user.
+2. Fetch the lnurl pay request static endpoint (`https://host.com/.well-known/lnurlp/user`) and gather the `allowsNostr` and `nostrPubkey` fields. If `allowsNostr` exists and it is `true`, and if `nostrPubkey` exists and is a valid BIP 340 public key in hex, associate this information with the user. The `nostrPubkey` is the `zapper`'s pubkey, and it is used to authorize zaps sent to that user.
 
 3. Clients may choose to display a lightning zap button on each post or on the users profile, if the user's lnurl pay request endpoint supports nostr, the client SHOULD generate a `zap invoice` instead of a normal lnurl invoice.