diff --git a/moli-core/tests/fixtures/runtime/locked_body.js b/moli-core/tests/fixtures/runtime/locked_body.js
new file mode 100644
index 0000000000..2cb4b80fe7
--- /dev/null
+++ b/moli-core/tests/fixtures/runtime/locked_body.js
@@ -0,0 +1,47 @@
+async function runLockedBodyProbe(url) {
+  const errors = [];
+  const check = (value, label) => { if (!value) errors.push(label); };
+  const throwsTypeError = (callback, label) => {
+    try { callback(); errors.push(label + ': accepted'); }
+    catch (error) { check(error instanceof TypeError, label + ': wrong error ' + error); }
+  };
+  const rejectsTypeError = async (callback, label) => {
+    let promise;
+    try { promise = callback(); }
+    catch (error) { errors.push(label + ': synchronous throw ' + error); return; }
+    try { await promise; errors.push(label + ': fulfilled'); }
+    catch (error) { check(error instanceof TypeError, label + ': wrong rejection ' + error); }
+  };
+  const methods = ['text', 'json', 'arrayBuffer', 'bytes', 'blob', 'formData'];
+  const streamFrom = value => new ReadableStream({
+    start(controller) { controller.enqueue(new TextEncoder().encode(value)); controller.close(); }
+  });
+  const makeBody = async (source, method = 'text') => {
+    const text = method === 'formData' ? 'name=value' : '{"value":1}';
+    const headers = {'Content-Type': method === 'formData'
+      ? 'application/x-www-form-urlencoded' : 'application/json'};
+    if (source === 'request') return new Request(url, {method: 'POST', body: text, headers});
+    if (source === 'response') return new Response(text, {headers});
+    if (source === 'stream') return new Response(streamFrom(text), {headers});
+    return fetch(url);
+  };
+  const sources = ['request', 'response', 'stream', 'fetch'];
+
+    for (const source of sources) {
+      for (const method of methods) {
+        const body = await makeBody(source, method);
+        const reader = body.body.getReader();
+        Object.defineProperty(body.body, 'locked', {get() {
+          throw new Error('public locked getter consulted');
+        }});
+        check(!body.bodyUsed, source + ': locking alone does not disturb');
+        throwsTypeError(() => body.clone(), source + ': locked clone');
+        await rejectsTypeError(() => body[method](), source + ': locked ' + method);
+        check(!body.bodyUsed, source + ': failed ' + method + ' must not disturb');
+        reader.releaseLock();
+        try { await body.text(); }
+        catch (error) { errors.push(source + ': released unused body cannot be consumed ' + error); }
+      }
+    }
+  return {errors};
+}
diff --git a/moli-core/tests/fixtures/runtime/web_streams.html b/moli-core/tests/fixtures/runtime/web_streams.html
index b31e1d0c01..20fcf0c80c 100644
--- a/moli-core/tests/fixtures/runtime/web_streams.html
+++ b/moli-core/tests/fixtures/runtime/web_streams.html
@@ -11,6 +11,7 @@
     <script>
       (async () => {
         const response = new Response('hello world');
+        const textResponse = response.clone();
         const reader = response.body.getReader();
         const first = await reader.read();
         document.body.setAttribute(
@@ -18,7 +19,18 @@
           new TextDecoder().decode(first.value),
         );
 
-        document.body.setAttribute('data-response-text', await response.text());
+        reader.releaseLock();
+        let consumedBodyRejected = false;
+        try {
+          await response.text();
+        } catch (error) {
+          if (!(error instanceof TypeError)) throw error;
+          consumedBodyRejected = true;
+        }
+        if (!consumedBodyRejected || !response.bodyUsed) {
+          throw new Error('Consumed Response body must remain unusable');
+        }
+        document.body.setAttribute('data-response-text', await textResponse.text());
 
         const input = new ReadableStream({
           start(controller) {
diff --git a/moli-core/tests/web_apis.rs b/moli-core/tests/web_apis.rs
index 1271244c31..c91312b6e5 100644
--- a/moli-core/tests/web_apis.rs
+++ b/moli-core/tests/web_apis.rs
@@ -1,3 +1,6 @@
+#[path = "web_apis/locked_body.rs"]
+mod locked_body;
+
 #[path = "web_apis/body_utf8.rs"]
 mod body_utf8;
 
diff --git a/moli-core/tests/web_apis/locked_body.rs b/moli-core/tests/web_apis/locked_body.rs
new file mode 100644
index 0000000000..716958ea00
--- /dev/null
+++ b/moli-core/tests/web_apis/locked_body.rs
@@ -0,0 +1,22 @@
+use super::*;
+
+#[tokio::test(flavor = "multi_thread")]
+async fn locked_bodies_reject_consumption_and_clone_without_becoming_disturbed() -> Result<()> {
+    let server = FixtureServer::spawn().await?;
+    let browser = Browser::new(AppConfig::default())?;
+    let source = format!(
+        "{}\nrunLockedBodyProbe({}).then(finish, error => finish({{error: String(error)}}));",
+        include_str!("../fixtures/runtime/locked_body.js"),
+        serde_json::to_string(&server.url("/compat/child-dynamic-markup-document"))?,
+    );
+    for target in ["window", "child", "worker"] {
+        let observed = tokio::time::timeout(
+            Duration::from_secs(20),
+            super::pipe_disturbed::run_probe(&browser, &server, target, &source),
+        )
+        .await??;
+        assert_eq!(observed, serde_json::json!({"errors": []}), "{target}");
+    }
+    server.shutdown().await;
+    Ok(())
+}
diff --git a/moli-renderer-v8/src/context_bootstrap.rs b/moli-renderer-v8/src/context_bootstrap.rs
index 123f251dd1..85916e183d 100644
--- a/moli-renderer-v8/src/context_bootstrap.rs
+++ b/moli-renderer-v8/src/context_bootstrap.rs
@@ -426,7 +426,8 @@ pub use self::storage_buckets::{
 };
 pub(crate) use self::stream_adapter::{
     cancel_readable_stream, close_stream, enqueue_byte_chunk, error_stream,
-    readable_stream_disturbed, readable_stream_has_pipe_owner, require_internal_stream_value,
+    readable_stream_disturbed, readable_stream_has_pipe_owner, readable_stream_locked,
+    require_internal_stream_value,
 };
 pub(crate) use self::streams::{
     ReadableStreamClonePayload, TransformStreamClonePayload, WritableStreamClonePayload,
diff --git a/moli-renderer-v8/src/context_bootstrap/stream_adapter.rs b/moli-renderer-v8/src/context_bootstrap/stream_adapter.rs
index 0b188dc693..924df6eca6 100644
--- a/moli-renderer-v8/src/context_bootstrap/stream_adapter.rs
+++ b/moli-renderer-v8/src/context_bootstrap/stream_adapter.rs
@@ -107,8 +107,8 @@ pub(in crate::context_bootstrap) use readable_state::{
 };
 pub(crate) use readable_state::{close_stream, enqueue_chunk, error_stream};
 pub(super) use readable_state::{
-    readable_stream_closed, readable_stream_error, readable_stream_locked,
-    reject_pending_read_requests, remove_pending_closed_promise, writable_stream_locked,
+    readable_stream_closed, readable_stream_error, reject_pending_read_requests,
+    remove_pending_closed_promise, writable_stream_locked,
 };
 pub(in crate::context_bootstrap::stream_adapter) use transform_finish::transform_stream_readable_cancel_callback;
 pub(super) use utils::{
@@ -140,6 +140,7 @@ pub(in crate::context_bootstrap::stream_adapter) use read_request::{
     error_read_request, fulfill_read_request, new_internal_read_request,
 };
 pub(in crate::context_bootstrap::stream_adapter) use readable_state::enqueue_pending_closed_promise;
+pub(crate) use readable_state::readable_stream_locked;
 pub(in crate::context_bootstrap::stream_adapter) use readable_state::{
     enqueue_pending_read, finish_readable_stream_close,
     readable_stream_controller_algorithm_object, readable_stream_controller_algorithm_value,
diff --git a/moli-renderer-v8/src/context_bootstrap/stream_adapter/readable_state.rs b/moli-renderer-v8/src/context_bootstrap/stream_adapter/readable_state.rs
index 4c49169ec3..e39916299b 100644
--- a/moli-renderer-v8/src/context_bootstrap/stream_adapter/readable_state.rs
+++ b/moli-renderer-v8/src/context_bootstrap/stream_adapter/readable_state.rs
@@ -568,7 +568,7 @@ fn reject_readable_stream_closed_promises<'s>(
     );
 }
 
-pub(in crate::context_bootstrap) fn readable_stream_locked<'s>(
+pub(crate) fn readable_stream_locked<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     stream: v8::Local<'s, v8::Object>,
 ) -> bool {
diff --git a/moli-renderer-v8/src/network_host.rs b/moli-renderer-v8/src/network_host.rs
index f2b3d67d65..80a25b4b65 100644
--- a/moli-renderer-v8/src/network_host.rs
+++ b/moli-renderer-v8/src/network_host.rs
@@ -37,7 +37,9 @@ pub(crate) use self::async_fetch::{
 };
 pub(crate) use self::beacon::{navigator_send_beacon_callback, send_link_audit_ping};
 pub(super) use self::bindings::install_window_network_bindings;
-pub(in crate::network_host) use self::body::{PreparedBodyInit, body_init};
+pub(in crate::network_host) use self::body::{
+    PreparedBodyInit, body_init, body_stream_object, readable_body_stream_unusable,
+};
 pub(crate) use self::body::{append_default_body_content_type, has_header};
 #[cfg(test)]
 pub(crate) use self::body_source::pending_network_body_source_buffered_len_for_test;
diff --git a/moli-renderer-v8/src/network_host/body.rs b/moli-renderer-v8/src/network_host/body.rs
index 6d7f25c004..425951b952 100644
--- a/moli-renderer-v8/src/network_host/body.rs
+++ b/moli-renderer-v8/src/network_host/body.rs
@@ -6,6 +6,27 @@ pub(in crate::network_host) const URL_SEARCH_PARAMS_CONTENT_TYPE: &str =
     "application/x-www-form-urlencoded;charset=UTF-8";
 pub(in crate::network_host) const TEXT_CONTENT_TYPE: &str = "text/plain;charset=UTF-8";
 
+pub(in crate::network_host) fn body_stream_object<'s>(
+    scope: &mut v8::PinScope<'s, '_>,
+    object: v8::Local<'s, v8::Object>,
+) -> Option<v8::Local<'s, v8::Object>> {
+    if is_branded_request_object(scope, object) {
+        request_slot_object(scope, object, REQUEST_BODY_SLOT)
+    } else if is_branded_response_object(scope, object) {
+        response_slot_object(scope, object, RESPONSE_BODY_SLOT)
+    } else {
+        None
+    }
+}
+
+pub(in crate::network_host) fn readable_body_stream_unusable<'s>(
+    scope: &mut v8::PinScope<'s, '_>,
+    stream: v8::Local<'s, v8::Object>,
+) -> bool {
+    crate::context_bootstrap::readable_stream_locked(scope, stream)
+        || crate::context_bootstrap::readable_stream_disturbed(scope, stream)
+}
+
 #[derive(Debug, Clone)]
 pub(in crate::network_host) struct PreparedBodyInit {
     pub(in crate::network_host) bytes: Vec<u8>,
diff --git a/moli-renderer-v8/src/network_host/fetch_surface.rs b/moli-renderer-v8/src/network_host/fetch_surface.rs
index 79aa1faeda..e2ed926006 100644
--- a/moli-renderer-v8/src/network_host/fetch_surface.rs
+++ b/moli-renderer-v8/src/network_host/fetch_surface.rs
@@ -800,7 +800,10 @@ fn request_clone_callback<'s>(
     let Some(this) = require_request_receiver(scope, args.this()) else {
         return;
     };
-    if body_already_used(scope, this, REQUEST_BODY_USED_SLOT) {
+    if body_already_used(scope, this, REQUEST_BODY_USED_SLOT)
+        || body_stream_object(scope, this)
+            .is_some_and(|stream| readable_body_stream_unusable(scope, stream))
+    {
         throw_type_error(
             scope,
             "Failed to execute 'clone' on 'Request': body stream already used",
@@ -831,7 +834,10 @@ fn response_clone_callback<'s>(
     let Some(this) = require_response_receiver(scope, args.this()) else {
         return;
     };
-    if body_already_used(scope, this, RESPONSE_BODY_USED_SLOT) {
+    if body_already_used(scope, this, RESPONSE_BODY_USED_SLOT)
+        || body_stream_object(scope, this)
+            .is_some_and(|stream| readable_body_stream_unusable(scope, stream))
+    {
         throw_type_error(
             scope,
             "Failed to execute 'clone' on 'Response': body stream already used",
diff --git a/moli-renderer-v8/src/network_host/response/body_methods.rs b/moli-renderer-v8/src/network_host/response/body_methods.rs
index 6878e40a74..8f831d1c31 100644
--- a/moli-renderer-v8/src/network_host/response/body_methods.rs
+++ b/moli-renderer-v8/src/network_host/response/body_methods.rs
@@ -208,6 +208,11 @@ fn begin_body_consumption<'s>(
     object: v8::Local<'s, v8::Object>,
     receiver: BodyReceiver,
 ) -> bool {
+    if body_stream_object(scope, object)
+        .is_some_and(|stream| readable_body_stream_unusable(scope, stream))
+    {
+        return false;
+    }
     match receiver {
         BodyReceiver::Response => {
             if response_slot_bool(scope, object, RESPONSE_BODY_USED_SLOT) {