diff --git a/modules/saml/docs/sp.md b/modules/saml/docs/sp.md
index 2579f27a3b6456a19fcbb11508c6b3ea401c21e6..fb9dff3aeb22bbb08cbcde2983b8081e7058baf4 100644
--- a/modules/saml/docs/sp.md
+++ b/modules/saml/docs/sp.md
@@ -126,6 +126,10 @@ Options
     arrays format as seen in the [Metadata endpoints](./simplesamlphp-metadata-endpoints)
     documentation.
 
+`AssertionConsumerServiceIndex`
+:   The Assertion Consumer Service Index to be used in the AuthnRequest in place of the Assertion
+    Service Consumer URL.
+
 `attributes`
 :   List of attributes this SP requests from the IdP.
     This list will be added to the generated metadata.