diff --git a/browser/components/doh/TRRPerformance.jsm b/browser/components/doh/TRRPerformance.jsm
index f410b438f458..3e024d34dfda 100644
--- a/browser/components/doh/TRRPerformance.jsm
+++ b/browser/components/doh/TRRPerformance.jsm
@@ -59,21 +59,9 @@ XPCOMUtils.defineLazyServiceGetter(
 );
 
 // The list of participating TRRs.
-XPCOMUtils.defineLazyPreferenceGetter(
-  this,
-  "kTRRs",
-  "network.trr.resolvers",
-  null,
-  null,
-  val =>
-    val
-      ? JSON.parse(val).map(trr => trr.url)
-      : [
-          "https://mozilla.cloudflare-dns.com/dns-query",
-          "https://trr.dns.nextdns.io/",
-          "https://doh.xfinity.com/dns-query",
-        ]
-);
+const kTRRs = JSON.parse(
+  Services.prefs.getDefaultBranch("").getCharPref("network.trr.resolvers")
+).map(trr => trr.url);
 
 // The canonical domain whose subdomains we will be resolving.
 XPCOMUtils.defineLazyPreferenceGetter(
diff --git a/browser/components/doh/test/unit/head.js b/browser/components/doh/test/unit/head.js
index d2790b9a60c2..9d2125eefd64 100644
--- a/browser/components/doh/test/unit/head.js
+++ b/browser/components/doh/test/unit/head.js
@@ -15,9 +15,7 @@ const { TestUtils } = ChromeUtils.import(
 );
 
 let h2Port, trrServer1, trrServer2;
-const { DNSLookup, LookupAggregator, TRRRacer } = ChromeUtils.import(
-  "resource:///modules/TRRPerformance.jsm"
-);
+let DNSLookup, LookupAggregator, TRRRacer;
 
 function readFile(file) {
   let fstream = Cc["@mozilla.org/network/file-input-stream;1"].createInstance(
@@ -75,11 +73,6 @@ function setup() {
   );
   addCertFromFile(certdb, "http2-ca.pem", "CTu,u,u");
 
-  Services.prefs.setCharPref(
-    "network.trr.resolvers",
-    `[{"url": "${trrServer1}"}, {"url": "${trrServer2}"}]`
-  );
-
   Services.prefs.setIntPref("doh-rollout.trrRace.randomSubdomainCount", 2);
 
   Services.prefs.setCharPref(
@@ -92,6 +85,24 @@ function setup() {
     "firefox-dns-perf-test.net"
   );
 
+  let defaultPrefBranch = Services.prefs.getDefaultBranch("");
+  let origResolverList = defaultPrefBranch.getCharPref("network.trr.resolvers");
+
+  Services.prefs
+    .getDefaultBranch("")
+    .setCharPref(
+      "network.trr.resolvers",
+      `[{"url": "${trrServer1}"}, {"url": "${trrServer2}"}]`
+    );
+
+  let TRRPerformance = ChromeUtils.import(
+    "resource:///modules/TRRPerformance.jsm"
+  );
+
+  DNSLookup = TRRPerformance.DNSLookup;
+  LookupAggregator = TRRPerformance.LookupAggregator;
+  TRRRacer = TRRPerformance.TRRRacer;
+
   let oldCanRecord = Services.telemetry.canRecordExtended;
   Services.telemetry.canRecordExtended = true;
 
@@ -99,7 +110,7 @@ function setup() {
     Services.prefs.clearUserPref("network.http.spdy.enabled");
     Services.prefs.clearUserPref("network.http.spdy.enabled.http2");
     Services.prefs.clearUserPref("network.dns.native-is-localhost");
-    Services.prefs.clearUserPref("network.trr.resolvers");
+    defaultPrefBranch.setCharPref("network.trr.resolvers", origResolverList);
 
     Services.telemetry.canRecordExtended = oldCanRecord;
   });