diff --git a/index.bs b/index.bs
index 3f8425f..b87bd7f 100644
--- a/index.bs
+++ b/index.bs
@@ -278,7 +278,7 @@ spec:css-syntax-3;
Same-Origin with its Ancestors
- An [=environment settings object=] (|settings|) is same-origin with its
+ An [=environment settings object=] (|settings|) is same-origin with its
ancestors if the following algorithm returns `true`: