diff --git a/index.bs b/index.bs
index d1e550c5..47b17e43 100644
--- a/index.bs
+++ b/index.bs
@@ -2810,7 +2810,7 @@ dimensions of a [=client window=].
 
       browser.SetClientWindowStateParameters = {
         clientWindow: browser.ClientWindow,
-        browser.ClientWindowNamedState // browser.ClientWindowRectState
+        (browser.ClientWindowNamedState // browser.ClientWindowRectState)
       }
 
       browser.ClientWindowNamedState = (