diff --git a/README.md b/README.md
index d5c3545..92d8071 100644
--- a/README.md
+++ b/README.md
@@ -24,10 +24,13 @@ It will return an ID of a new captcha in plaintext.
 
 ### Get an image for a captcha
 
-    GET /:captcha_id/image
+    GET /:captcha_id/image?style=
 
 Responds with an image (e.g. in PNG format).
 
+An optional query parameter `style=` could be supplied if captcha implementation
+support different styles.
+
 #### HTTP codes
 - `200` if exists
 - `404` if doesn't exist