--- a/netwerk/base/security-prefs.js
+++ b/netwerk/base/security-prefs.js
@@ -1,14 +1,14 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 pref("security.tls.version.min", 1);
-pref("security.tls.version.max", 3);
+pref("security.tls.version.max", 4);
 pref("security.tls.version.fallback-limit", 3);
 pref("security.tls.insecure_fallback_hosts", "");
 pref("security.tls.unrestricted_rc4_fallback", false);
 pref("security.tls.enable_0rtt_data", false);
 
 pref("security.ssl.treat_unsafe_negotiation_as_broken", false);
 pref("security.ssl.require_safe_negotiation",  false);
 pref("security.ssl.enable_ocsp_stapling", true);

--- a/security/manager/ssl/nsNSSComponent.cpp
+++ b/security/manager/ssl/nsNSSComponent.cpp
@@ -1649,17 +1649,17 @@ void nsNSSComponent::setValidationOption
 // Enable the TLS versions given in the prefs, defaulting to TLS 1.0 (min) and
 // TLS 1.2 (max) when the prefs aren't set or set to invalid values.
 nsresult
 nsNSSComponent::setEnabledTLSVersions()
 {
   // keep these values in sync with security-prefs.js
   // 1 means TLS 1.0, 2 means TLS 1.1, etc.
   static const uint32_t PSM_DEFAULT_MIN_TLS_VERSION = 1;
-  static const uint32_t PSM_DEFAULT_MAX_TLS_VERSION = 3;
+  static const uint32_t PSM_DEFAULT_MAX_TLS_VERSION = 4;
 
   uint32_t minFromPrefs = Preferences::GetUint("security.tls.version.min",
                                                PSM_DEFAULT_MIN_TLS_VERSION);
   uint32_t maxFromPrefs = Preferences::GetUint("security.tls.version.max",
                                                PSM_DEFAULT_MAX_TLS_VERSION);
 
   SSLVersionRange defaults = {
     SSL_LIBRARY_VERSION_3_0 + PSM_DEFAULT_MIN_TLS_VERSION,