diff --git a/README.md b/README.md
index 6f38043..16366e7 100644
--- a/README.md
+++ b/README.md
@@ -158,10 +158,10 @@ Options:
           The path prefix act as a secret to authenticate clients
           Disabled by default. Accept all path prefix. Can be specified multiple time
       --tls-certificate <FILE_PATH>
-          [Optional] Use custom certificate (.crt) instead of the default embedded self signed certificate.
+          [Optional] Use custom certificate (.pem) instead of the default embedded self signed certificate.
           The certificate will be automatically reloaded if it changes 
       --tls-private-key <FILE_PATH>
-          [Optional] Use a custom tls key (.key) that the server will use instead of the default embedded one
+          [Optional] Use a custom tls key (.pem) that the server will use instead of the default embedded one
           The private key will be automatically reloaded if it changes
   -h, --help
           Print help