diff --git a/testing/web-platform/tests/client-hints/accept-ch-cache-revalidation.https.html b/testing/web-platform/tests/client-hints/accept-ch-cache-revalidation.https.html
index 217a490ba5c8f..60c61603b3956 100644
--- a/testing/web-platform/tests/client-hints/accept-ch-cache-revalidation.https.html
+++ b/testing/web-platform/tests/client-hints/accept-ch-cache-revalidation.https.html
@@ -23,7 +23,6 @@
"rtt",
"downlink",
"ect",
- "lang",
"sec-ch-ua",
"sec-ch-ua-arch",
"sec-ch-ua-platform",
diff --git a/testing/web-platform/tests/client-hints/http-equiv-accept-ch-merge.https.html b/testing/web-platform/tests/client-hints/http-equiv-accept-ch-merge.https.html
index 4ed2291de2999..940554b928692 100644
--- a/testing/web-platform/tests/client-hints/http-equiv-accept-ch-merge.https.html
+++ b/testing/web-platform/tests/client-hints/http-equiv-accept-ch-merge.https.html
@@ -1,7 +1,7 @@
-
+
@@ -19,7 +19,6 @@
// Verify that the browser includes client hints in the headers.
assert_true(r.headers.has("device-memory-received"), "device-memory-received");
assert_true(r.headers.has("dpr-received"), "dpr-received");
- assert_true(r.headers.has("lang-received"), "lang-received");
assert_true(r.headers.has("viewport-width-received"), "viewport-width-received");
assert_true(r.headers.has("rtt-received"), "rtt-received");
diff --git a/testing/web-platform/tests/client-hints/resources/echo-client-hints-received.py b/testing/web-platform/tests/client-hints/resources/echo-client-hints-received.py
index 798e380237d36..0aa4faeed932e 100644
--- a/testing/web-platform/tests/client-hints/resources/echo-client-hints-received.py
+++ b/testing/web-platform/tests/client-hints/resources/echo-client-hints-received.py
@@ -22,8 +22,6 @@ def main(request, response):
response.headers.set(b"downlink-received", request.headers.get(b"downlink"))
if b"ect" in request.headers:
response.headers.set(b"ect-received", request.headers.get(b"ect"))
- if b"Lang" in request.headers:
- response.headers.set(b"lang-received", request.headers.get(b"Lang"))
if b"sec-ch-ua-mobile" in request.headers:
response.headers.set(b"mobile-received", request.headers.get(b"sec-ch-ua-mobile"))
if b"sec-ch-prefers-color-scheme" in request.headers:
diff --git a/testing/web-platform/tests/client-hints/resources/stale-echo-client-hints.py b/testing/web-platform/tests/client-hints/resources/stale-echo-client-hints.py
index a9caae80ccc86..f4d2fb2647305 100644
--- a/testing/web-platform/tests/client-hints/resources/stale-echo-client-hints.py
+++ b/testing/web-platform/tests/client-hints/resources/stale-echo-client-hints.py
@@ -16,7 +16,6 @@ def main(request, response):
b"rtt",
b"downlink",
b"ect",
- b"lang",
b"sec-ch-ua",
b"sec-ch-ua-arch",
b"sec-ch-ua-platform",