diff --git a/20.md b/20.md
index 4bf1b598..1d01739d 100644
--- a/20.md
+++ b/20.md
@@ -39,6 +39,26 @@ with the requested `amount`,`unit`, and `description` according to [NUT-04][04].
 >
 > **Privacy:** To prevent the mint from being able to link multiple mint quotes, wallets **SHOULD** generate a unique public key for each mint quote request.
 
+### Deterministic quote locking key derivation
+
+Wallets can deterministically generate private keys for NUT-20 quote locking from their wallet seed.
+
+The following BIP32 derivation path is used to derive the private key:
+
+```
+m/129373'/20'/0'/0'/{counter}
+```
+
+Where:
+
+- `129373'` is the Cashu wallet derivation namespace.
+- `20'` is the wallet derivation index for NUT-20 quote locking keys.
+- `{counter}` is an incrementing, non-hardened BIP32 child index.
+
+The wallet **SHOULD** use a new counter value for each mint quote request. The NUT-20 quote locking counter is independent from NUT-13 keyset counters and other wallet derivation counters.
+
+The wallet uses the compressed secp256k1 public key derived from the private key as the quote `pubkey`. This allows a wallet to restore the private key needed to sign for unpaid or paid NUT-20 locked mint quotes during a recovery process.
+
 The mint `Bob` then responds with a `PostMintQuoteBolt11Response`:
 
 ```json
diff --git a/tests/20-test.md b/tests/20-test.md
index e534f948..f3344b55 100644
--- a/tests/20-test.md
+++ b/tests/20-test.md
@@ -1,5 +1,27 @@
 # NUT-20 Test Vectors
 
+## Deterministic quote locking key derivation
+
+Using [NUT-20](../20.md) quote locking key derivation, we derive values starting from the following BIP39 mnemonic:
+
+```json
+{
+  "mnemonic": "half depart obvious quality work element tank gorilla view sugar picture humble"
+}
+```
+
+The public keys derived for the first five counters from `counter=0` to `counter=4` are:
+
+```json
+{
+  "m/129373'/20'/0'/0'/0": "03062837166e56114b59a4d1fd3a5a812bf7aadc1dde758428cf943d80acd41539",
+  "m/129373'/20'/0'/0'/1": "02b47d9d41725f5ce6f08c874835cef25376cb1e95f6cb073fef52ca8fd986cf15",
+  "m/129373'/20'/0'/0'/2": "029acbd3a46fd75bc05ba0226d0b4d909b2fb6e96c80544a094a1a3567737e44d3",
+  "m/129373'/20'/0'/0'/3": "0373e4a42fbe0a4e18aadb57cf500b655f2446b4071ee579121d2ed8905bcc49c2",
+  "m/129373'/20'/0'/0'/4": "02b8709bfce17c10f1864f5218844533ae60930d52089669b317d8b5f474eec071"
+}
+```
+
 The following is a `PostMintBolt11Request` with a valid signature. Where the `pubkey` in the `PostMintQuoteBolt11Request` is `03d56ce4e446a85bbdaa547b4ec2b073d40ff802831352b8272b7dd7a4de5a7cac`.
 
 ```json