diff --git a/docs/basics.md b/docs/basics.md
index fcfd36006..0e20bb66e 100644
--- a/docs/basics.md
+++ b/docs/basics.md
@@ -236,7 +236,7 @@ The following rules are both `Matchers` and `Modifiers`, so the `Matcher` portio
 By default, routes will be sorted (in descending order) using rules length (to avoid path overlap):
 `PathPrefix:/12345` will be matched before `PathPrefix:/1234` that will be matched before `PathPrefix:/1`.
 
-You can customize priority by frontend:
+You can customize priority by frontend. The priority value is added to the rule length during sorting:
 
 ```toml
   [frontends]
@@ -254,7 +254,7 @@ You can customize priority by frontend:
       rule = "PathPrefix:/toto"
 ```
 
-Here, `frontend1` will be matched before `frontend2` (`10 > 5`).
+Here, `frontend1` will be matched before `frontend2` (`(3 + 10 == 13) > (4 + 5 == 9)`).
 
 #### Custom headers