diff --git a/index.html b/index.html
index 8b6511e..c32a059 100644
--- a/index.html
+++ b/index.html
@@ -574,9 +574,18 @@
The subscribe() method when invoked MUST run the following steps:
- - Let |promise| be [=a new promise=].
+
- Let |global| be the [=relevant global object=] of [=this=].
- - Let |global| be [=this=]' [=relevant global object=].
+
- If |global| is a {{Window}} object:
+
+ - If |global| does not have [=transient activation=], return [=a promise rejected
+ with=] with a {{"NotAllowedError"}} {{DOMException}}.
+
+ - [=Consume user activation=] of |global|.
+
+
+
+ - Let |promise| be a new promise.
- Return |promise| and continue [=in parallel=].