diff --git a/README.md b/README.md
index 4725d8c..690c9b6 100644
--- a/README.md
+++ b/README.md
@@ -14,3 +14,6 @@ Currently stores no state and has no user authentication, so using it should jus
   POST /game/{id}/move
   GET /game/{id}/move/{movenum}
 ```
+
+## Authorization headers
+  Requests should contain header "Player-id"="red|blue"