diff --git a/ca.conf.sample b/ca.conf.sample
index a4ec7df..977005a 100644
--- a/ca.conf.sample
+++ b/ca.conf.sample
@@ -10,7 +10,7 @@
   ]
   "supported-challenges":
   [
-    { "challenge": "PIN" },
-    { "challenge": "Email" }
+    { "challenge": "pin" },
+    { "challenge": "email" }
   ]
 }