diff --git a/Stateless-Mode.md b/Stateless-Mode.md
index edc5eb87..40fd4295 100644
--- a/Stateless-Mode.md
+++ b/Stateless-Mode.md
@@ -85,7 +85,7 @@ Configure your webserver to respond statelessly to challenges for a given accoun
         mode  http
         bind :80
         bind :443 ssl crt /etc/haproxy/certs/
-        http-request return status 200 content-type text/plain lf-string "%[path,field(-1,/)].${ACCOUNT_THUMBPRINT}\n" if { path_beg '/.well-known/acme-challenge/' }
+        http-request return status 200 content-type text/plain lf-string "%[path,field(-1,/)].${ACCOUNT_THUMBPRINT}\n" if { path_reg '^/.well-known/acme-challenge/[-_a-zA-Z0-9]+$' }
     ```
 3. Ok, you can issue cert now.
   ```