diff --git a/dom/ipc/tests/mochitest.ini b/dom/ipc/tests/mochitest.ini
index 185334689d6..177b37df22d 100644
--- a/dom/ipc/tests/mochitest.ini
+++ b/dom/ipc/tests/mochitest.ini
@@ -16,7 +16,7 @@ skip-if = buildapp == 'b2g' || buildapp == 'mulet'
 [test_NuwaProcessCreation.html]
 skip-if = toolkit != 'gonk'
 [test_NuwaProcessDeadlock.html]
-skip-if = true # bug 1166923
+skip-if = toolkit != 'gonk'
 [test_child_docshell.html]
 skip-if = toolkit == 'cocoa' # disabled due to hangs, see changeset 6852e7c47edf
 [test_CrashService_crash.html]
diff --git a/dom/ipc/tests/test_NuwaProcessDeadlock.html b/dom/ipc/tests/test_NuwaProcessDeadlock.html
index 1029aa1aa9b..150707f5b3b 100644
--- a/dom/ipc/tests/test_NuwaProcessDeadlock.html
+++ b/dom/ipc/tests/test_NuwaProcessDeadlock.html
@@ -14,6 +14,9 @@ Test if Nuwa process created successfully.
 
 function runTest()
 {
+  info("Shut down processes by disabling process prelaunch");
+  SpecialPowers.setBoolPref('dom.ipc.processPrelaunch.enabled', false);
+
   info("Launch the Nuwa process");
   let cpmm = SpecialPowers.Cc["@mozilla.org/childprocessmessagemanager;1"]
                           .getService(SpecialPowers.Ci.nsISyncMessageSender);
@@ -22,12 +25,11 @@ function runTest()
     receiveMessage: function receiveMessage(msg) {
       msg = SpecialPowers.wrap(msg);
       if (msg.name == 'TEST-ONLY:nuwa-ready') {
-        ok(true, "Got nuwa-ready");
-        is(seenNuwaReady, false, "Already received nuwa ready");
+        is(seenNuwaReady, false, "The Nuwa process is launched");
         seenNuwaReady = true;
       } else if (msg.name == 'TEST-ONLY:nuwa-add-new-process') {
         ok(true, "Got nuwa-add-new-process");
-        is(seenNuwaReady, true, "Receive nuwa-add-new-process before nuwa-ready");
+        is(seenNuwaReady, true, "The preallocated process is launched from the Nuwa process");
         shutdown();
       }
     }
@@ -51,12 +53,11 @@ function runTest()
 
 function setup()
 {
-  info("Set up preferences for testing deadlock in the Nuwa process.");
+  info("Set up preferences for testing the Nuwa process.");
   SimpleTest.waitForExplicitFinish();
 
   SpecialPowers.pushPrefEnv({
     'set': [
-      ['dom.ipc.processPrelaunch.enabled', false],
       ['dom.ipc.preallocatedProcessManager.testMode', true],
       ['dom.ipc.processPrelaunch.testMode', true]  // For testing deadlock
     ]
diff --git a/xpcom/threads/TimerThread.cpp b/xpcom/threads/TimerThread.cpp
index 2bf92bc999f..9eeda7a93c7 100644
--- a/xpcom/threads/TimerThread.cpp
+++ b/xpcom/threads/TimerThread.cpp
@@ -430,7 +430,11 @@ TimerThread::Run()
     bool forceRunThisTimer = forceRunNextTimer;
     forceRunNextTimer = false;
 
-    if (mSleeping) {
+    if (mSleeping
+#ifdef MOZ_NUWA_PROCESS
+        || IsNuwaProcess() // Don't fire timers or deadlock will result.
+#endif
+        ) {
       // Sleep for 0.1 seconds while not firing timers.
       uint32_t milliseconds = 100;
       if (ChaosMode::isActive(ChaosFeature::TimerScheduling)) {