diff --git a/API.md b/API.md
index 28b9692..7b9839c 100644
--- a/API.md
+++ b/API.md
@@ -5,7 +5,7 @@ All API endpoints are based off of `/api` if you access Radarr via `http://local
 
 ## Authentication ##
 
-All requests made to the api endpoint require API Key authentication using the X-Api-Key header.
+All requests made to the api endpoint require API Key authentication using the X-Api-Key header or in the query string using `?apikey=APIKEY`.
 
 ### API Key ###