diff --git a/docs/index.md b/docs/index.md
index c63b7709..4cda3442 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -40,6 +40,7 @@ simple message using a POST request:
     ``` http
     POST /mytopic HTTP/1.1
     Host: ntfy.sh
+    Content-Length: 22
     
     Backup successful 😀
     ```