diff --git a/browser_patches/firefox-beta/BUILD_NUMBER b/browser_patches/firefox-beta/BUILD_NUMBER
index 5b8aa349f0..7c8389789d 100644
--- a/browser_patches/firefox-beta/BUILD_NUMBER
+++ b/browser_patches/firefox-beta/BUILD_NUMBER
@@ -1,2 +1,2 @@
-1296
-Changed: lushnikov@chromium.org Thu 14 Oct 2021 12:01:09 PM PDT
+1297
+Changed: lushnikov@chromium.org Fri Oct 15 18:52:51 PDT 2021
diff --git a/browser_patches/firefox-beta/juggler/NetworkObserver.js b/browser_patches/firefox-beta/juggler/NetworkObserver.js
index d9e383adf1..9efa8a1825 100644
--- a/browser_patches/firefox-beta/juggler/NetworkObserver.js
+++ b/browser_patches/firefox-beta/juggler/NetworkObserver.js
@@ -540,6 +540,11 @@ class NetworkRequest {
 
   // nsIStreamListener
   onDataAvailable(aRequest, aInputStream, aOffset, aCount) {
+    // Turns out webcompat shims might redirect to
+    // SimpleChannel, so we get requests from a different channel.
+    // See https://github.com/microsoft/playwright/issues/9418#issuecomment-944836244
+    if (aRequest !== this.httpChannel)
+      return;
     // For requests with internal redirect (e.g. intercepted by Service Worker),
     // we do not get onResponse normally, but we do get nsIStreamListener notifications.
     this._sendOnResponse(false);
@@ -562,6 +567,11 @@ class NetworkRequest {
 
   // nsIStreamListener
   onStartRequest(aRequest) {
+    // Turns out webcompat shims might redirect to
+    // SimpleChannel, so we get requests from a different channel.
+    // See https://github.com/microsoft/playwright/issues/9418#issuecomment-944836244
+    if (aRequest !== this.httpChannel)
+      return;
     try {
       this._originalListener.onStartRequest(aRequest);
     } catch (e) {
@@ -571,6 +581,11 @@ class NetworkRequest {
 
   // nsIStreamListener
   onStopRequest(aRequest, aStatusCode) {
+    // Turns out webcompat shims might redirect to
+    // SimpleChannel, so we get requests from a different channel.
+    // See https://github.com/microsoft/playwright/issues/9418#issuecomment-944836244
+    if (aRequest !== this.httpChannel)
+      return;
     try {
       this._originalListener.onStopRequest(aRequest, aStatusCode);
     } catch (e) {
diff --git a/browser_patches/firefox/BUILD_NUMBER b/browser_patches/firefox/BUILD_NUMBER
index b773a86693..cee08010e5 100644
--- a/browser_patches/firefox/BUILD_NUMBER
+++ b/browser_patches/firefox/BUILD_NUMBER
@@ -1,2 +1,2 @@
-1296
-Changed: lushnikov@chromium.org Wed Oct 13 15:47:14 PDT 2021
+1297
+Changed: lushnikov@chromium.org Fri Oct 15 18:51:16 PDT 2021
diff --git a/browser_patches/firefox/juggler/NetworkObserver.js b/browser_patches/firefox/juggler/NetworkObserver.js
index d9e383adf1..9efa8a1825 100644
--- a/browser_patches/firefox/juggler/NetworkObserver.js
+++ b/browser_patches/firefox/juggler/NetworkObserver.js
@@ -540,6 +540,11 @@ class NetworkRequest {
 
   // nsIStreamListener
   onDataAvailable(aRequest, aInputStream, aOffset, aCount) {
+    // Turns out webcompat shims might redirect to
+    // SimpleChannel, so we get requests from a different channel.
+    // See https://github.com/microsoft/playwright/issues/9418#issuecomment-944836244
+    if (aRequest !== this.httpChannel)
+      return;
     // For requests with internal redirect (e.g. intercepted by Service Worker),
     // we do not get onResponse normally, but we do get nsIStreamListener notifications.
     this._sendOnResponse(false);
@@ -562,6 +567,11 @@ class NetworkRequest {
 
   // nsIStreamListener
   onStartRequest(aRequest) {
+    // Turns out webcompat shims might redirect to
+    // SimpleChannel, so we get requests from a different channel.
+    // See https://github.com/microsoft/playwright/issues/9418#issuecomment-944836244
+    if (aRequest !== this.httpChannel)
+      return;
     try {
       this._originalListener.onStartRequest(aRequest);
     } catch (e) {
@@ -571,6 +581,11 @@ class NetworkRequest {
 
   // nsIStreamListener
   onStopRequest(aRequest, aStatusCode) {
+    // Turns out webcompat shims might redirect to
+    // SimpleChannel, so we get requests from a different channel.
+    // See https://github.com/microsoft/playwright/issues/9418#issuecomment-944836244
+    if (aRequest !== this.httpChannel)
+      return;
     try {
       this._originalListener.onStopRequest(aRequest, aStatusCode);
     } catch (e) {