diff --git a/fetch.bs b/fetch.bs
index 8d19ae84d..b87736ae6 100755
--- a/fetch.bs
+++ b/fetch.bs
@@ -4659,6 +4659,18 @@ the response. [[!HTTP-CACHING]]
    <var>request</var>'s <a for=request>header list</a>.
   </ol>
 
+ <li>
+  <p>If <var>request</var>'s <a for=request>header list</a> <a for="header list">does not contain</a> `<code>Accept-Language</code>` and
+  <var>request</var>'s <a for=request>client</a> is non-null:
+
+  <ol>
+   <li><p>Let <var>emulatedLanguage</var> be the <a>WebDriver BiDi emulated language</a>
+   for <var>request</var>'s <a for=request>client</a>.
+
+   <li><p>If <var>emulatedLanguage</var> is not null, <a for="header list">append</a>(`<code>Accept-Language</code>, <var>emulatedLanguage</var>)
+   to <var>request</var>'s <a for=request>header list</a>.
+  </ol>
+
  <li><p>If <var>request</var>'s <a for=request>header list</a>
  <a for="header list">does not contain</a> `<code>Accept-Language</code>`, then user agents should
  <a for="header list">append</a> (`<code>Accept-Language</code>, an appropriate