--- a/browser/components/resistfingerprinting/test/browser/browser_navigator.js
+++ b/browser/components/resistfingerprinting/test/browser/browser_navigator.js
@@ -113,18 +113,17 @@ async function testWorkerNavigator() {
   await BrowserTestUtils.removeTab(tab);
 }
 
 add_task(async function setup() {
   await SpecialPowers.pushPrefEnv({"set":
     [["privacy.resistFingerprinting", true]]
   });
 
-  let appVersion = parseInt(Services.appinfo.version);
-  let spoofedVersion = appVersion - ((appVersion - 3) % 7);
+  let spoofedVersion = 52;
   spoofedUserAgent = `Mozilla/5.0 (${SPOOFED_UA_OS[AppConstants.platform]}; rv:${spoofedVersion}.0) Gecko/20100101 Firefox/${spoofedVersion}.0`;
 });
 
 add_task(async function runNavigatorTest() {
   await testNavigator();
 });
 
 add_task(async function runWorkerNavigatorTest() {

--- a/toolkit/components/resistfingerprinting/nsRFPService.cpp
+++ b/toolkit/components/resistfingerprinting/nsRFPService.cpp
@@ -242,56 +242,22 @@ nsRFPService::GetSpoofedUserAgent(nsACSt
 {
   // This function generates the spoofed value of User Agent.
   // We spoof the values of the platform and Firefox version, which could be
   // used as fingerprinting sources to identify individuals.
   // Reference of the format of User Agent:
   // https://developer.mozilla.org/en-US/docs/Web/API/NavigatorID/userAgent
   // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/User-Agent
 
-  nsresult rv;
-  nsCOMPtr<nsIXULAppInfo> appInfo =
-    do_GetService("@mozilla.org/xre/app-info;1", &rv);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  nsAutoCString appVersion;
-  rv = appInfo->GetVersion(appVersion);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  // The browser version will be spoofed as the last ESR version.
-  // By doing so, the anonymity group will cover more versions instead of one
-  // version.
-  uint32_t firefoxVersion = appVersion.ToInteger(&rv);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  // Starting from Firefox 10, Firefox ESR was released once every seven
-  // Firefox releases, e.g. Firefox 10, 17, 24, 31, and so on.
-  // We infer the last and closest ESR version based on this rule.
-  nsCOMPtr<nsIXULRuntime> runtime =
-    do_GetService("@mozilla.org/xre/runtime;1", &rv);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  nsAutoCString updateChannel;
-  rv = runtime->GetDefaultUpdateChannel(updateChannel);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  // If we are running in Firefox ESR, determine whether the formula of ESR
-  // version has changed.  Once changed, we must update the formula in this
-  // function.
-  if (updateChannel.EqualsLiteral("esr")) {
-    MOZ_ASSERT(((firefoxVersion % 7) == 3),
-      "Please udpate ESR version formula in nsRFPService.cpp");
-  }
-
-  uint32_t spoofedVersion = firefoxVersion - ((firefoxVersion - 3) % 7);
+  uint32_t spoofedVersion = 52;
   userAgent.Assign(nsPrintfCString(
     "Mozilla/5.0 (%s; rv:%d.0) Gecko/%s Firefox/%d.0",
     SPOOFED_UA_OS, spoofedVersion, LEGACY_BUILD_ID, spoofedVersion));
 
-  return rv;
+  return NS_OK;
 }
 
 nsresult
 nsRFPService::Init()
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   nsresult rv;