diff --git a/devtools/client/debugger/test/mochitest/head.js b/devtools/client/debugger/test/mochitest/head.js
index 43dd3ed9df238..ec3668e74d0be 100644
--- a/devtools/client/debugger/test/mochitest/head.js
+++ b/devtools/client/debugger/test/mochitest/head.js
@@ -13,6 +13,7 @@ Services.scriptloader.loadSubScript("chrome://mochitests/content/browser/devtool
 // be affected by this pref.
 var gEnableLogging = Services.prefs.getBoolPref("devtools.debugger.log");
 Services.prefs.setBoolPref("devtools.debugger.log", false);
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
 
 var { BrowserToolboxProcess } = ChromeUtils.import("resource://devtools/client/framework/ToolboxProcess.jsm", {});
 var { DebuggerServer } = require("devtools/server/main");
@@ -37,6 +38,7 @@ const CHROME_URI = Services.io.newURI(CHROME_URL);
 registerCleanupFunction(async function() {
   info("finish() was called, cleaning up...");
   Services.prefs.setBoolPref("devtools.debugger.log", gEnableLogging);
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
 
   while (gBrowser && gBrowser.tabs && gBrowser.tabs.length > 1) {
     info("Destroying toolbox.");
diff --git a/devtools/client/shared/test/browser_dbg_listworkers.js b/devtools/client/shared/test/browser_dbg_listworkers.js
index 7150acc952f83..679fcef2ceb5f 100644
--- a/devtools/client/shared/test/browser_dbg_listworkers.js
+++ b/devtools/client/shared/test/browser_dbg_listworkers.js
@@ -5,6 +5,12 @@
 
 "use strict";
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 // Import helpers for the workers
 /* import-globals-from helper_workers.js */
 Services.scriptloader.loadSubScript(
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
index fc10ebe8baa21..8a56767f948af 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
@@ -4,6 +4,12 @@
 
 "use strict";
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 // Test dynamic updates in the storage inspector for cookies.
 
 add_task(async function() {
diff --git a/devtools/server/tests/unit/test_framebindings-01.js b/devtools/server/tests/unit/test_framebindings-01.js
index 5e877aa8e75ce..aff653b258a7d 100644
--- a/devtools/server/tests/unit/test_framebindings-01.js
+++ b/devtools/server/tests/unit/test_framebindings-01.js
@@ -11,6 +11,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-stack");
diff --git a/devtools/server/tests/unit/test_framebindings-02.js b/devtools/server/tests/unit/test_framebindings-02.js
index f8f0dcd33c2cd..8582cfb46901e 100644
--- a/devtools/server/tests/unit/test_framebindings-02.js
+++ b/devtools/server/tests/unit/test_framebindings-02.js
@@ -11,6 +11,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-stack");
diff --git a/devtools/server/tests/unit/test_framebindings-03.js b/devtools/server/tests/unit/test_framebindings-03.js
index 044db6eab8a9e..c5df8cb70c5fe 100644
--- a/devtools/server/tests/unit/test_framebindings-03.js
+++ b/devtools/server/tests/unit/test_framebindings-03.js
@@ -12,6 +12,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-stack");
diff --git a/devtools/server/tests/unit/test_framebindings-04.js b/devtools/server/tests/unit/test_framebindings-04.js
index 9a4b489385fca..8d748dba6554e 100644
--- a/devtools/server/tests/unit/test_framebindings-04.js
+++ b/devtools/server/tests/unit/test_framebindings-04.js
@@ -13,6 +13,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-stack");
diff --git a/devtools/server/tests/unit/test_framebindings-05.js b/devtools/server/tests/unit/test_framebindings-05.js
index 268abc6244485..04c2526ecdb31 100644
--- a/devtools/server/tests/unit/test_framebindings-05.js
+++ b/devtools/server/tests/unit/test_framebindings-05.js
@@ -12,6 +12,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-stack");
diff --git a/devtools/server/tests/unit/test_framebindings-06.js b/devtools/server/tests/unit/test_framebindings-06.js
index 9a383c0bd7146..fb8a6382880ca 100644
--- a/devtools/server/tests/unit/test_framebindings-06.js
+++ b/devtools/server/tests/unit/test_framebindings-06.js
@@ -7,6 +7,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-grips");
diff --git a/devtools/server/tests/unit/test_framebindings-07.js b/devtools/server/tests/unit/test_framebindings-07.js
index 18fd870ab96f9..ff96e6dccfc57 100644
--- a/devtools/server/tests/unit/test_framebindings-07.js
+++ b/devtools/server/tests/unit/test_framebindings-07.js
@@ -8,6 +8,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 // Test that the EnvironmentClient's getBindings() method works as expected.
 function run_test() {
   initTestDebuggerServer();
diff --git a/devtools/server/tests/unit/test_longstringgrips-01.js b/devtools/server/tests/unit/test_longstringgrips-01.js
index 3d5b295519b3d..0e10e5d1da3d5 100644
--- a/devtools/server/tests/unit/test_longstringgrips-01.js
+++ b/devtools/server/tests/unit/test_longstringgrips-01.js
@@ -7,6 +7,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-grips");
diff --git a/devtools/server/tests/unit/test_longstringgrips-02.js b/devtools/server/tests/unit/test_longstringgrips-02.js
index 9bcaa8f5651a0..70ecf3a40330b 100644
--- a/devtools/server/tests/unit/test_longstringgrips-02.js
+++ b/devtools/server/tests/unit/test_longstringgrips-02.js
@@ -7,6 +7,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-grips");
diff --git a/devtools/server/tests/unit/test_objectgrips-04.js b/devtools/server/tests/unit/test_objectgrips-04.js
index 976337c050a6f..5cefe33d532d4 100644
--- a/devtools/server/tests/unit/test_objectgrips-04.js
+++ b/devtools/server/tests/unit/test_objectgrips-04.js
@@ -9,6 +9,12 @@ var gClient;
 var gThreadClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-05.js b/devtools/server/tests/unit/test_objectgrips-05.js
index f516a3ac21470..cbce64d847077 100644
--- a/devtools/server/tests/unit/test_objectgrips-05.js
+++ b/devtools/server/tests/unit/test_objectgrips-05.js
@@ -13,6 +13,12 @@ var gClient;
 var gThreadClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-06.js b/devtools/server/tests/unit/test_objectgrips-06.js
index 8ed806de78ccc..76e8227ccd32c 100644
--- a/devtools/server/tests/unit/test_objectgrips-06.js
+++ b/devtools/server/tests/unit/test_objectgrips-06.js
@@ -13,6 +13,12 @@ var gClient;
 var gThreadClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-07.js b/devtools/server/tests/unit/test_objectgrips-07.js
index f258f88d87eba..338606d56877f 100644
--- a/devtools/server/tests/unit/test_objectgrips-07.js
+++ b/devtools/server/tests/unit/test_objectgrips-07.js
@@ -13,6 +13,12 @@ var gClient;
 var gThreadClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-08.js b/devtools/server/tests/unit/test_objectgrips-08.js
index 4b0cc159aaf93..6d2a097c08a88 100644
--- a/devtools/server/tests/unit/test_objectgrips-08.js
+++ b/devtools/server/tests/unit/test_objectgrips-08.js
@@ -8,6 +8,12 @@ var gClient;
 var gThreadClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-09.js b/devtools/server/tests/unit/test_objectgrips-09.js
index aed5c056e75a1..c3e97b627cced 100644
--- a/devtools/server/tests/unit/test_objectgrips-09.js
+++ b/devtools/server/tests/unit/test_objectgrips-09.js
@@ -13,6 +13,12 @@ var gClient;
 var gThreadClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-10.js b/devtools/server/tests/unit/test_objectgrips-10.js
index 7714d333f435a..c40aef6e0976f 100644
--- a/devtools/server/tests/unit/test_objectgrips-10.js
+++ b/devtools/server/tests/unit/test_objectgrips-10.js
@@ -8,6 +8,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 // Test that closures can be inspected.
 
 function run_test() {
diff --git a/devtools/server/tests/unit/test_objectgrips-11.js b/devtools/server/tests/unit/test_objectgrips-11.js
index 40e89cc70e64d..123986c5fdbf4 100644
--- a/devtools/server/tests/unit/test_objectgrips-11.js
+++ b/devtools/server/tests/unit/test_objectgrips-11.js
@@ -9,6 +9,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-grips");
diff --git a/devtools/server/tests/unit/test_objectgrips-12.js b/devtools/server/tests/unit/test_objectgrips-12.js
index 32d6295bb25ed..fb948fc957d88 100644
--- a/devtools/server/tests/unit/test_objectgrips-12.js
+++ b/devtools/server/tests/unit/test_objectgrips-12.js
@@ -12,6 +12,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-grips");
diff --git a/devtools/server/tests/unit/test_objectgrips-16.js b/devtools/server/tests/unit/test_objectgrips-16.js
index e05d3cc505e43..27c7c7fa9c345 100644
--- a/devtools/server/tests/unit/test_objectgrips-16.js
+++ b/devtools/server/tests/unit/test_objectgrips-16.js
@@ -9,6 +9,12 @@ var gClient;
 var gThreadClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-17.js b/devtools/server/tests/unit/test_objectgrips-17.js
index fa3d8246d75dc..bbb4a05d1ac86 100644
--- a/devtools/server/tests/unit/test_objectgrips-17.js
+++ b/devtools/server/tests/unit/test_objectgrips-17.js
@@ -14,6 +14,12 @@ var gGlobalIsInvisible;
 var gSubsumes;
 var gIsOpaque;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-18.js b/devtools/server/tests/unit/test_objectgrips-18.js
index ce99437d99859..631a0e574a9ce 100644
--- a/devtools/server/tests/unit/test_objectgrips-18.js
+++ b/devtools/server/tests/unit/test_objectgrips-18.js
@@ -9,6 +9,12 @@ var gClient;
 var gThreadClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-19.js b/devtools/server/tests/unit/test_objectgrips-19.js
index 8e6989d7124aa..4c1d7eea1b309 100644
--- a/devtools/server/tests/unit/test_objectgrips-19.js
+++ b/devtools/server/tests/unit/test_objectgrips-19.js
@@ -7,6 +7,12 @@
 var gDebuggee;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-20.js b/devtools/server/tests/unit/test_objectgrips-20.js
index 4af7cabdf35f1..0916ca8406907 100644
--- a/devtools/server/tests/unit/test_objectgrips-20.js
+++ b/devtools/server/tests/unit/test_objectgrips-20.js
@@ -8,6 +8,12 @@
 // when passing `ignoreNonIndexedProperties` and `ignoreIndexedProperties` options
 // with various objects. (See Bug 1403065)
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 async function run_test() {
   do_test_pending();
   await run_test_with_server(DebuggerServer);
diff --git a/devtools/server/tests/unit/test_objectgrips-21.js b/devtools/server/tests/unit/test_objectgrips-21.js
index 52b2ffaef4713..73306bb6e9f4c 100644
--- a/devtools/server/tests/unit/test_objectgrips-21.js
+++ b/devtools/server/tests/unit/test_objectgrips-21.js
@@ -7,6 +7,12 @@
 var gDebuggee;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/devtools/server/tests/unit/test_objectgrips-22.js b/devtools/server/tests/unit/test_objectgrips-22.js
index 025efc2868294..d09425abeae24 100644
--- a/devtools/server/tests/unit/test_objectgrips-22.js
+++ b/devtools/server/tests/unit/test_objectgrips-22.js
@@ -7,6 +7,12 @@
 var gDebuggee;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 add_task(async function run_test() {
   await run_test_with_server(DebuggerServer);
   await run_test_with_server(WorkerDebuggerServer);
diff --git a/devtools/server/tests/unit/test_objectgrips-array-like-object.js b/devtools/server/tests/unit/test_objectgrips-array-like-object.js
index ad531fc136456..ed458a8a9e994 100644
--- a/devtools/server/tests/unit/test_objectgrips-array-like-object.js
+++ b/devtools/server/tests/unit/test_objectgrips-array-like-object.js
@@ -7,6 +7,12 @@
 // numeric keys, and if they have a length property, that it matches the number
 // of numeric keys. (See Bug 1371936)
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 async function run_test() {
   do_test_pending();
   await run_test_with_server(DebuggerServer);
diff --git a/devtools/server/tests/unit/test_objectgrips-fn-apply-01.js b/devtools/server/tests/unit/test_objectgrips-fn-apply-01.js
index 2f4b493f06493..4c76ccdfc1bf2 100644
--- a/devtools/server/tests/unit/test_objectgrips-fn-apply-01.js
+++ b/devtools/server/tests/unit/test_objectgrips-fn-apply-01.js
@@ -4,6 +4,12 @@
 
 "use strict";
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 async function run_test() {
   try {
     do_test_pending();
diff --git a/devtools/server/tests/unit/test_objectgrips-fn-apply-02.js b/devtools/server/tests/unit/test_objectgrips-fn-apply-02.js
index fbeb882333701..120f9df0307b5 100644
--- a/devtools/server/tests/unit/test_objectgrips-fn-apply-02.js
+++ b/devtools/server/tests/unit/test_objectgrips-fn-apply-02.js
@@ -4,6 +4,12 @@
 
 "use strict";
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 async function run_test() {
   try {
     do_test_pending();
diff --git a/devtools/server/tests/unit/test_objectgrips-fn-apply-03.js b/devtools/server/tests/unit/test_objectgrips-fn-apply-03.js
index 58cd354da1575..cb5e59ff2aad5 100644
--- a/devtools/server/tests/unit/test_objectgrips-fn-apply-03.js
+++ b/devtools/server/tests/unit/test_objectgrips-fn-apply-03.js
@@ -4,6 +4,12 @@
 
 "use strict";
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 async function run_test() {
   try {
     do_test_pending();
diff --git a/devtools/server/tests/unit/test_objectgrips-property-value-01.js b/devtools/server/tests/unit/test_objectgrips-property-value-01.js
index 154037aebcaee..76e633c1e6cb4 100644
--- a/devtools/server/tests/unit/test_objectgrips-property-value-01.js
+++ b/devtools/server/tests/unit/test_objectgrips-property-value-01.js
@@ -4,6 +4,12 @@
 
 "use strict";
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 async function run_test() {
   try {
     do_test_pending();
diff --git a/devtools/server/tests/unit/test_objectgrips-property-value-02.js b/devtools/server/tests/unit/test_objectgrips-property-value-02.js
index 67ec6358ca793..baa58b1677c93 100644
--- a/devtools/server/tests/unit/test_objectgrips-property-value-02.js
+++ b/devtools/server/tests/unit/test_objectgrips-property-value-02.js
@@ -4,6 +4,12 @@
 
 "use strict";
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 async function run_test() {
   try {
     do_test_pending();
diff --git a/devtools/server/tests/unit/test_pause_exceptions-01.js b/devtools/server/tests/unit/test_pause_exceptions-01.js
index e2c0a15739231..97b4005c83ee5 100644
--- a/devtools/server/tests/unit/test_pause_exceptions-01.js
+++ b/devtools/server/tests/unit/test_pause_exceptions-01.js
@@ -13,6 +13,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-stack");
diff --git a/devtools/server/tests/unit/test_pause_exceptions-02.js b/devtools/server/tests/unit/test_pause_exceptions-02.js
index 7778034908244..1dc724072ace5 100644
--- a/devtools/server/tests/unit/test_pause_exceptions-02.js
+++ b/devtools/server/tests/unit/test_pause_exceptions-02.js
@@ -12,6 +12,12 @@ var gDebuggee;
 var gClient;
 var gThreadClient;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   initTestDebuggerServer();
   gDebuggee = addTestGlobal("test-stack");
diff --git a/devtools/server/tests/unit/test_stepping-05.js b/devtools/server/tests/unit/test_stepping-05.js
index 8d63d1dad4956..5485ddffb2894 100644
--- a/devtools/server/tests/unit/test_stepping-05.js
+++ b/devtools/server/tests/unit/test_stepping-05.js
@@ -14,6 +14,12 @@ var gDebuggee;
 var gClient;
 var gCallback;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   run_test_with_server(DebuggerServer, function() {
     run_test_with_server(WorkerDebuggerServer, do_test_finished);
diff --git a/dom/plugins/test/mochitest/test_hangui.xul b/dom/plugins/test/mochitest/test_hangui.xul
index 317d18d973caf..12f19ad9d3107 100644
--- a/dom/plugins/test/mochitest/test_hangui.xul
+++ b/dom/plugins/test/mochitest/test_hangui.xul
@@ -22,6 +22,8 @@
 <![CDATA[
 SimpleTest.waitForExplicitFinish();
 SimpleTest.expectChildProcessCrash();
+SpecialPowers.pushPrefEnv({"set": [["security.allow_eval_with_system_principal",
+                                    true]]});
 setTestPluginEnabledState(SpecialPowers.Ci.nsIPluginTag.STATE_ENABLED);
 
 ChromeUtils.import("resource://gre/modules/Services.jsm");
diff --git a/intl/uconv/tests/unit/test_bug340714.js b/intl/uconv/tests/unit/test_bug340714.js
index f2d8e4d7f04af..a4ca7bf275a1c 100644
--- a/intl/uconv/tests/unit/test_bug340714.js
+++ b/intl/uconv/tests/unit/test_bug340714.js
@@ -12,6 +12,7 @@
  */
 
 ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
+ChromeUtils.import("resource://gre/modules/Services.jsm");
 
 const beBOM="%FE%FF";
 const leBOM="%FF%FE";
@@ -19,6 +20,11 @@ const sampleUTF16BE="%00%22%04%12%04%41%04%35%00%20%04%41%04%47%04%30%04%41%04%4
 const sampleUTF16LE="%22%00%12%04%41%04%35%04%20%00%41%04%47%04%30%04%41%04%42%04%3B%04%38%04%32%04%4B%04%35%04%20%00%41%04%35%04%3C%04%4C%04%38%04%20%00%3F%04%3E%04%45%04%3E%04%36%04%38%04%20%00%34%04%40%04%43%04%33%04%20%00%3D%04%30%04%20%00%34%04%40%04%43%04%33%04%30%04%2C%00%20%00%3A%04%30%04%36%04%34%04%30%04%4F%04%20%00%3D%04%35%04%41%04%47%04%30%04%41%04%42%04%3B%04%38%04%32%04%30%04%4F%04%20%00%41%04%35%04%3C%04%4C%04%4F%04%20%00%3D%04%35%04%41%04%47%04%30%04%41%04%42%04%3B%04%38%04%32%04%30%04%20%00%3F%04%3E%04%2D%00%41%04%32%04%3E%04%35%04%3C%04%43%04%2E%00%22%00";
 const expected = "\"\u0412\u0441\u0435 \u0441\u0447\u0430\u0441\u0442\u043B\u0438\u0432\u044B\u0435 \u0441\u0435\u043C\u044C\u0438 \u043F\u043E\u0445\u043E\u0436\u0438 \u0434\u0440\u0443\u0433 \u043D\u0430 \u0434\u0440\u0443\u0433\u0430, \u043A\u0430\u0436\u0434\u0430\u044F \u043D\u0435\u0441\u0447\u0430\u0441\u0442\u043B\u0438\u0432\u0430\u044F \u0441\u0435\u043C\u044C\u044F \u043D\u0435\u0441\u0447\u0430\u0441\u0442\u043B\u0438\u0432\u0430 \u043F\u043E-\u0441\u0432\u043E\u0435\u043C\u0443.\"";
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function makeText(withBOM, charset)
 {
   var theText = eval("sample" + charset);
diff --git a/js/ductwork/debugger/tests/test_nativewrappers.js b/js/ductwork/debugger/tests/test_nativewrappers.js
index 7cf49a6f1a061..1b71df0e2f656 100644
--- a/js/ductwork/debugger/tests/test_nativewrappers.js
+++ b/js/ductwork/debugger/tests/test_nativewrappers.js
@@ -1,6 +1,13 @@
 function run_test()
 {
   ChromeUtils.import("resource://gre/modules/jsdebugger.jsm");
+  ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+  Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+  });
+
   addDebuggerToGlobal(this);
   var g = testGlobal("test1");
 
diff --git a/js/xpconnect/tests/chrome/test_bug732665.xul b/js/xpconnect/tests/chrome/test_bug732665.xul
index 63af7af6361e1..a3ec323dcb400 100644
--- a/js/xpconnect/tests/chrome/test_bug732665.xul
+++ b/js/xpconnect/tests/chrome/test_bug732665.xul
@@ -18,6 +18,8 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=732665
   <script type="application/javascript">
   <![CDATA[
 
+  SpecialPowers.pushPrefEnv({"set": [["security.allow_eval_with_system_principal",
+                                       true]]});
   //
   // Important! If this test starts failing after a tricky platform-y change,
   // the stack quota numbers in XPCJSContext probably need twiddling. We want
diff --git a/js/xpconnect/tests/chrome/test_xrayToJS.xul b/js/xpconnect/tests/chrome/test_xrayToJS.xul
index 97def9ddf4eab..9f3fec553e057 100644
--- a/js/xpconnect/tests/chrome/test_xrayToJS.xul
+++ b/js/xpconnect/tests/chrome/test_xrayToJS.xul
@@ -18,6 +18,9 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=933681
   <script type="application/javascript">
   <![CDATA[
 
+  SpecialPowers.pushPrefEnv({"set": [["security.allow_eval_with_system_principal",
+                                       true]]});
+
   /** Test for ES constructors on Xrayed globals. **/
   SimpleTest.waitForExplicitFinish();
   let global = Cu.getGlobalForObject.bind(Cu);
diff --git a/js/xpconnect/tests/unit/test_ComponentEnvironment.js b/js/xpconnect/tests/unit/test_ComponentEnvironment.js
index c55b94873d8b2..d969e1c7c01a2 100644
--- a/js/xpconnect/tests/unit/test_ComponentEnvironment.js
+++ b/js/xpconnect/tests/unit/test_ComponentEnvironment.js
@@ -1,4 +1,12 @@
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
 let tgt = {};
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 const a = ChromeUtils.import("resource://test/environment_script.js", tgt);
 const b = ChromeUtils.import("resource://test/environment_checkscript.jsm", tgt);
 
diff --git a/js/xpconnect/tests/unit/test_FrameScriptEnvironment.js b/js/xpconnect/tests/unit/test_FrameScriptEnvironment.js
index 41b389b5d9e8d..084d510eab7a3 100644
--- a/js/xpconnect/tests/unit/test_FrameScriptEnvironment.js
+++ b/js/xpconnect/tests/unit/test_FrameScriptEnvironment.js
@@ -2,6 +2,11 @@ ChromeUtils.import("resource://gre/modules/Services.jsm");
 
 let ppmm = Services.ppmm.getChildAt(0);
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 add_task(async function test_bindings() {
     let {strict, bound} = await new Promise(function(resolve) {
         // Use a listener to get results from child
diff --git a/js/xpconnect/tests/unit/test_SubscriptLoaderEnvironment.js b/js/xpconnect/tests/unit/test_SubscriptLoaderEnvironment.js
index 7fe9ba77ee931..062df3bfe3cf9 100644
--- a/js/xpconnect/tests/unit/test_SubscriptLoaderEnvironment.js
+++ b/js/xpconnect/tests/unit/test_SubscriptLoaderEnvironment.js
@@ -1,6 +1,13 @@
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 
 let tgt = {};
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 Services.scriptloader.loadSubScript("resource://test/environment_script.js", tgt);
 
 var bound = "";
diff --git a/js/xpconnect/tests/unit/test_SubscriptLoaderJSMEnvironment.js b/js/xpconnect/tests/unit/test_SubscriptLoaderJSMEnvironment.js
index 76ec58450ea16..1f020d44e8dbb 100644
--- a/js/xpconnect/tests/unit/test_SubscriptLoaderJSMEnvironment.js
+++ b/js/xpconnect/tests/unit/test_SubscriptLoaderJSMEnvironment.js
@@ -1,5 +1,12 @@
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
 let tgt_load = {};
 let tgt_check = {};
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
 const a = ChromeUtils.import("resource://test/environment_loadscript.jsm", tgt_load);
 const b = ChromeUtils.import("resource://test/environment_checkscript.jsm", tgt_check);
 
diff --git a/js/xpconnect/tests/unit/test_SubscriptLoaderSandboxEnvironment.js b/js/xpconnect/tests/unit/test_SubscriptLoaderSandboxEnvironment.js
index 4b1085e2daeff..812da15877b24 100644
--- a/js/xpconnect/tests/unit/test_SubscriptLoaderSandboxEnvironment.js
+++ b/js/xpconnect/tests/unit/test_SubscriptLoaderSandboxEnvironment.js
@@ -1,6 +1,11 @@
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 
 let tgt = Cu.Sandbox(Services.scriptSecurityManager.getSystemPrincipal());
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
 Services.scriptloader.loadSubScript("resource://test/environment_script.js", tgt);
 
 var bound = "";
diff --git a/js/xpconnect/tests/unit/test_bug1244222.js b/js/xpconnect/tests/unit/test_bug1244222.js
index f9839103b1269..8b8958f429c5d 100644
--- a/js/xpconnect/tests/unit/test_bug1244222.js
+++ b/js/xpconnect/tests/unit/test_bug1244222.js
@@ -2,6 +2,13 @@
  * 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/. */
 
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   registerAppManifest(do_get_file('../components/js/xpctest.manifest'));
 
diff --git a/js/xpconnect/tests/unit/test_classesByID_instanceof.js b/js/xpconnect/tests/unit/test_classesByID_instanceof.js
index e14fbad1c7a8c..48bab684ff92c 100644
--- a/js/xpconnect/tests/unit/test_classesByID_instanceof.js
+++ b/js/xpconnect/tests/unit/test_classesByID_instanceof.js
@@ -1,3 +1,10 @@
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function testActual(CSPContextClassByID)
 {
   var cspContext =
diff --git a/js/xpconnect/tests/unit/test_onGarbageCollection-01.js b/js/xpconnect/tests/unit/test_onGarbageCollection-01.js
index 138f699f941df..016158d0d93a6 100644
--- a/js/xpconnect/tests/unit/test_onGarbageCollection-01.js
+++ b/js/xpconnect/tests/unit/test_onGarbageCollection-01.js
@@ -9,6 +9,13 @@ const NUM_SLICES = root.NUM_SLICES = 10;
 let fired = false;
 let slicesFound = 0;
 
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 dbg.memory.onGarbageCollection = data => {
   fired = true;
 
diff --git a/js/xpconnect/tests/unit/test_onGarbageCollection-02.js b/js/xpconnect/tests/unit/test_onGarbageCollection-02.js
index a8bf22c675b83..4901c4f6b413c 100644
--- a/js/xpconnect/tests/unit/test_onGarbageCollection-02.js
+++ b/js/xpconnect/tests/unit/test_onGarbageCollection-02.js
@@ -18,6 +18,13 @@ let fired2 = false;
 dbg1.memory.onGarbageCollection = _ => fired1 = true;
 dbg2.memory.onGarbageCollection = _ => fired2 = true;
 
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function reset() {
   fired1 = false;
   fired2 = false;
diff --git a/js/xpconnect/tests/unit/test_onGarbageCollection-03.js b/js/xpconnect/tests/unit/test_onGarbageCollection-03.js
index 1c7f158a76fa3..498eb5d029ad2 100644
--- a/js/xpconnect/tests/unit/test_onGarbageCollection-03.js
+++ b/js/xpconnect/tests/unit/test_onGarbageCollection-03.js
@@ -1,5 +1,11 @@
 // Test that the onGarbageCollection hook is not reentrant.
 
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
 
 function run_test() {
   do_test_pending();
diff --git a/js/xpconnect/tests/unit/test_onGarbageCollection-04.js b/js/xpconnect/tests/unit/test_onGarbageCollection-04.js
index a7c71b82ad376..9555bdf0c1f14 100644
--- a/js/xpconnect/tests/unit/test_onGarbageCollection-04.js
+++ b/js/xpconnect/tests/unit/test_onGarbageCollection-04.js
@@ -23,6 +23,13 @@
 // same time that we are preventing reentrancy into debuggeree's
 // onGarbageCollection hook.
 
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   do_test_pending();
 
diff --git a/js/xpconnect/tests/unit/test_onGarbageCollection-05.js b/js/xpconnect/tests/unit/test_onGarbageCollection-05.js
index a34859cebaa74..b13eb01307260 100644
--- a/js/xpconnect/tests/unit/test_onGarbageCollection-05.js
+++ b/js/xpconnect/tests/unit/test_onGarbageCollection-05.js
@@ -5,6 +5,13 @@ const root = newGlobal();
 const dbg = new Debugger();
 const wrappedRoot = dbg.addDebuggee(root)
 
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
   do_test_pending();
 
diff --git a/js/xpconnect/tests/unit/test_xrayed_iterator.js b/js/xpconnect/tests/unit/test_xrayed_iterator.js
index 0f012da6c74f1..a6b0b71c4f5a2 100644
--- a/js/xpconnect/tests/unit/test_xrayed_iterator.js
+++ b/js/xpconnect/tests/unit/test_xrayed_iterator.js
@@ -1,3 +1,10 @@
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test() {
 
   var toEval = [
diff --git a/netwerk/test/unit/test_chunked_responses.js b/netwerk/test/unit/test_chunked_responses.js
index 7867e42f790b0..29fe043887212 100644
--- a/netwerk/test/unit/test_chunked_responses.js
+++ b/netwerk/test/unit/test_chunked_responses.js
@@ -13,6 +13,12 @@
 
 ChromeUtils.import("resource://testing-common/httpd.js");
 ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
 
 XPCOMUtils.defineLazyGetter(this, "URL", function() {
   return "http://localhost:" + httpserver.identity.primaryPort;
diff --git a/netwerk/test/unit/test_content_length_underrun.js b/netwerk/test/unit/test_content_length_underrun.js
index 4fc00ef5b9a72..3bff3e3880613 100644
--- a/netwerk/test/unit/test_content_length_underrun.js
+++ b/netwerk/test/unit/test_content_length_underrun.js
@@ -7,6 +7,7 @@
 
 ChromeUtils.import("resource://testing-common/httpd.js");
 ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
+ChromeUtils.import("resource://gre/modules/Services.jsm");
 
 XPCOMUtils.defineLazyGetter(this, "URL", function() {
   return "http://localhost:" + httpserver.identity.primaryPort;
@@ -21,6 +22,11 @@ var prefs;
 var enforcePrefStrict;
 var enforcePrefSoft;
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 function run_test()
 {
   prefs = Cc["@mozilla.org/preferences-service;1"].getService(Ci.nsIPrefBranch);
diff --git a/services/sync/tests/unit/test_utils_deepEquals.js b/services/sync/tests/unit/test_utils_deepEquals.js
index c60e633ede156..f0280ef3de146 100644
--- a/services/sync/tests/unit/test_utils_deepEquals.js
+++ b/services/sync/tests/unit/test_utils_deepEquals.js
@@ -1,5 +1,11 @@
 _("Make sure Utils.deepEquals correctly finds items that are deeply equal");
 ChromeUtils.import("resource://services-sync/util.js");
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
 
 function run_test() {
   let data = '[NaN, undefined, null, true, false, Infinity, 0, 1, "a", "b", {a: 1}, {a: "a"}, [{a: 1}], [{a: true}], {a: 1, b: 2}, [1, 2], [1, 2, 3]]';
diff --git a/toolkit/components/contentprefs/tests/unit_cps2/test_observers.js b/toolkit/components/contentprefs/tests/unit_cps2/test_observers.js
index a5c3f11a2e867..96cab04bbae42 100644
--- a/toolkit/components/contentprefs/tests/unit_cps2/test_observers.js
+++ b/toolkit/components/contentprefs/tests/unit_cps2/test_observers.js
@@ -4,6 +4,13 @@
 
 let global = this;
 
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 add_task(async function resetBeforeTests() {
   await reset();
 });
diff --git a/toolkit/components/ctypes/tests/unit/test_jsctypes.js b/toolkit/components/ctypes/tests/unit/test_jsctypes.js
index 084a369741a06..305486c6d913b 100644
--- a/toolkit/components/ctypes/tests/unit/test_jsctypes.js
+++ b/toolkit/components/ctypes/tests/unit/test_jsctypes.js
@@ -9,6 +9,12 @@ try {
   // We might be running without privileges, in which case it's up to the
   // harness to give us the 'ctypes' object.
   ChromeUtils.import("resource://gre/modules/ctypes.jsm");
+  ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+  Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+  registerCleanupFunction(() => {
+    Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+  });
 } catch (e) {
 }
 
diff --git a/toolkit/components/feeds/test/test_xml.js b/toolkit/components/feeds/test/test_xml.js
index ad0fb56cd8742..152c34bbf9d8b 100644
--- a/toolkit/components/feeds/test/test_xml.js
+++ b/toolkit/components/feeds/test/test_xml.js
@@ -26,6 +26,12 @@
 "use strict";
 
 ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
+ChromeUtils.import("resource://gre/modules/Services.jsm");
+
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
 
 // Listens to feeds being loaded. Runs the tests built into the feed afterwards to veryify they
 // were parsed correctly.
diff --git a/toolkit/modules/tests/xpcshell/test_GMPInstallManager.js b/toolkit/modules/tests/xpcshell/test_GMPInstallManager.js
index 2bbe9a21e84fe..057e867358110 100644
--- a/toolkit/modules/tests/xpcshell/test_GMPInstallManager.js
+++ b/toolkit/modules/tests/xpcshell/test_GMPInstallManager.js
@@ -19,6 +19,11 @@ Cu.importGlobalProperties(["DOMParser"]);
 
 var ProductAddonCheckerScope = ChromeUtils.import("resource://gre/modules/addons/ProductAddonChecker.jsm", {});
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 do_get_profile();
 
 function run_test() {
diff --git a/toolkit/modules/tests/xpcshell/test_Log.js b/toolkit/modules/tests/xpcshell/test_Log.js
index 2a6c210965006..54c52e79556e8 100644
--- a/toolkit/modules/tests/xpcshell/test_Log.js
+++ b/toolkit/modules/tests/xpcshell/test_Log.js
@@ -8,6 +8,11 @@ ChromeUtils.import("resource://gre/modules/osfile.jsm");
 
 ChromeUtils.import("resource://gre/modules/Log.jsm");
 
+Services.prefs.setBoolPref("security.allow_eval_with_system_principal", true);
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref("security.allow_eval_with_system_principal");
+});
+
 var testFormatter = {
   format: function format(message) {
     return message.loggerName + "\t" +