diff --git a/.env.example b/.env.example
index b7fb9f06..898f90bd 100644
--- a/.env.example
+++ b/.env.example
@@ -103,3 +103,8 @@ ECLAIR_PASS=eclairpw
 # Enter /api in LightningTipBot to get your key
 LNTIPS_API_KEY=LNTIPS_ADMIN_KEY
 LNTIPS_API_ENDPOINT=https://ln.tips
+
+# Cashu Mint
+# Use a long-enough random (!) private key. 
+# Once set, you cannot change this key as for now.
+CASHU_PRIVATE_KEY="SuperSecretPrivateKey"