diff --git a/tools/profiler/tasktracer/GeckoTaskTracer.h b/tools/profiler/tasktracer/GeckoTaskTracer.h
index acb00e2af01..656513645c0 100644
--- a/tools/profiler/tasktracer/GeckoTaskTracer.h
+++ b/tools/profiler/tasktracer/GeckoTaskTracer.h
@@ -75,7 +75,8 @@ const PRTime GetStartTime();
 
 Task* CreateTracedTask(Task* aTask);
 
-already_AddRefed<nsIRunnable> CreateTracedRunnable(nsIRunnable* aRunnable);
+already_AddRefed<nsIRunnable>
+CreateTracedRunnable(already_AddRefed<nsIRunnable>&& aRunnable);
 
 // Free the TraceInfo allocated on a thread's TLS. Currently we are wrapping
 // tasks running on nsThreads and base::thread, so FreeTraceInfo is called at
diff --git a/tools/profiler/tasktracer/TracedTaskCommon.cpp b/tools/profiler/tasktracer/TracedTaskCommon.cpp
index 1794d2e7804..9fc2f559a50 100644
--- a/tools/profiler/tasktracer/TracedTaskCommon.cpp
+++ b/tools/profiler/tasktracer/TracedTaskCommon.cpp
@@ -90,9 +90,9 @@ TracedTaskCommon::ClearTLSTraceInfo()
 /**
  * Implementation of class TracedRunnable.
  */
-TracedRunnable::TracedRunnable(nsIRunnable* aOriginalObj)
+TracedRunnable::TracedRunnable(already_AddRefed<nsIRunnable>&& aOriginalObj)
   : TracedTaskCommon()
-  , mOriginalObj(aOriginalObj)
+  , mOriginalObj(Move(aOriginalObj))
 {
   Init();
   LogVirtualTablePtr(mTaskId, mSourceEventId, *(int**)(aOriginalObj));
@@ -148,9 +148,9 @@ TracedTask::Run()
  * nsIRunnable object, aRunnable.
  */
 already_AddRefed<nsIRunnable>
-CreateTracedRunnable(nsIRunnable* aRunnable)
+CreateTracedRunnable(already_AddRefed<nsIRunnable>&& aRunnable)
 {
-  nsCOMPtr<nsIRunnable> runnable = new TracedRunnable(aRunnable);
+  nsCOMPtr<nsIRunnable> runnable = new TracedRunnable(Move(aRunnable));
   return runnable.forget();
 }
 
diff --git a/tools/profiler/tasktracer/TracedTaskCommon.h b/tools/profiler/tasktracer/TracedTaskCommon.h
index b3c5fae0330..3594b8e9e95 100644
--- a/tools/profiler/tasktracer/TracedTaskCommon.h
+++ b/tools/profiler/tasktracer/TracedTaskCommon.h
@@ -46,7 +46,7 @@ class TracedRunnable : public TracedTaskCommon
 public:
   NS_DECL_NSIRUNNABLE
 
-  TracedRunnable(nsIRunnable* aOriginalObj);
+  TracedRunnable(already_AddRefed<nsIRunnable>&& aOriginalObj);
 
 private:
   virtual ~TracedRunnable();
diff --git a/xpcom/threads/nsThread.cpp b/xpcom/threads/nsThread.cpp
index f876ea770e3..7dc5f286af7 100644
--- a/xpcom/threads/nsThread.cpp
+++ b/xpcom/threads/nsThread.cpp
@@ -592,7 +592,7 @@ nsThread::DispatchInternal(already_AddRefed<nsIRunnable>&& aEvent, uint32_t aFla
   }
 
 #ifdef MOZ_TASK_TRACER
-  nsCOMPtr<nsIRunnable> tracedRunnable = CreateTracedRunnable(event); // adds a ref
+  nsCOMPtr<nsIRunnable> tracedRunnable = CreateTracedRunnable(event.forget());
   (static_cast<TracedRunnable*>(tracedRunnable.get()))->DispatchTask();
   event = tracedRunnable.forget();
 #endif