diff --git a/browser_patches/firefox-beta/BUILD_NUMBER b/browser_patches/firefox-beta/BUILD_NUMBER
index 2dbcc7d271..aebcbfe0e6 100644
--- a/browser_patches/firefox-beta/BUILD_NUMBER
+++ b/browser_patches/firefox-beta/BUILD_NUMBER
@@ -1,2 +1,2 @@
-1298
-Changed: lushnikov@chromium.org Tue 19 Oct 2021 05:01:45 PM PDT
+1299
+Changed: lushnikov@chromium.org Wed 27 Oct 2021 12:40:16 AM PDT
diff --git a/browser_patches/firefox-beta/patches/bootstrap.diff b/browser_patches/firefox-beta/patches/bootstrap.diff
index 90e523ba1e..0decaf1b78 100644
--- a/browser_patches/firefox-beta/patches/bootstrap.diff
+++ b/browser_patches/firefox-beta/patches/bootstrap.diff
@@ -1920,7 +1920,7 @@ index b32d426ba38045d14e6f1e79d17e8e6061e78227..df782034e79466fcc251e9a06e99d2e1
    }
  
 diff --git a/js/src/vm/DateTime.cpp b/js/src/vm/DateTime.cpp
-index e8f27fb69691aa6062c860a14ec94660fb9e5189..dd0218a5c2b3f2908f1549b8ef44a73df062b50e 100644
+index e8f27fb69691aa6062c860a14ec94660fb9e5189..67715cbbc8257f11927564b45bbc8ee5384f809d 100644
 --- a/js/src/vm/DateTime.cpp
 +++ b/js/src/vm/DateTime.cpp
 @@ -170,6 +170,11 @@ void js::DateTimeInfo::internalResetTimeZone(ResetTimeZoneMode mode) {
@@ -1964,16 +1964,15 @@ index e8f27fb69691aa6062c860a14ec94660fb9e5189..dd0218a5c2b3f2908f1549b8ef44a73d
  
  void js::DateTimeInfo::internalResyncICUDefaultTimeZone() {
  #if JS_HAS_INTL_API
--  if (const char* tzenv = std::getenv("TZ")) {
--    std::string_view tz(tzenv);
-+  std::string_view tz;
 +  if (!timeZoneOverride_.empty()) {
-+    tz = timeZoneOverride_;
-+  } else if (const char* tzenv = std::getenv("TZ")) {
-+    tz = std::string_view(tzenv);
++    mozilla::Span<const char> tzid = mozilla::Span(timeZoneOverride_.data(), timeZoneOverride_.length());
++    mozilla::intl::TimeZone::SetDefaultTimeZone(tzid);
++    return;
 +  }
- 
-+  if (!tz.empty()) {
++
+   if (const char* tzenv = std::getenv("TZ")) {
+     std::string_view tz(tzenv);
+-
      mozilla::Span<const char> tzid;
  
  #  if defined(XP_WIN)