diff --git a/xpcom/glue/MainThreadUtils.h b/xpcom/glue/MainThreadUtils.h
index e03f39f69dd5..8d76f84ec5c8 100644
--- a/xpcom/glue/MainThreadUtils.h
+++ b/xpcom/glue/MainThreadUtils.h
@@ -17,7 +17,7 @@ class nsIThread;
  * @param aResult
  *   The resulting nsIThread object.
  */
-extern NS_METHOD NS_GetMainThread(nsIThread** aResult);
+extern nsresult NS_GetMainThread(nsIThread** aResult);
 
 #ifdef MOZILLA_INTERNAL_API
 // Fast access to the current thread.  Do not release the returned pointer!  If
diff --git a/xpcom/glue/nsThreadUtils.cpp b/xpcom/glue/nsThreadUtils.cpp
index 8f80cfebb5ad..541555dedd68 100644
--- a/xpcom/glue/nsThreadUtils.cpp
+++ b/xpcom/glue/nsThreadUtils.cpp
@@ -55,7 +55,7 @@ CancelableRunnable::Cancel()
 
 //-----------------------------------------------------------------------------
 
-NS_METHOD
+nsresult
 NS_NewThread(nsIThread** aResult, nsIRunnable* aEvent, uint32_t aStackSize)
 {
   nsCOMPtr<nsIThread> thread;
@@ -89,7 +89,7 @@ NS_NewThread(nsIThread** aResult, nsIRunnable* aEvent, uint32_t aStackSize)
   return NS_OK;
 }
 
-NS_METHOD
+nsresult
 NS_GetCurrentThread(nsIThread** aResult)
 {
 #ifdef MOZILLA_INTERNAL_API
@@ -105,7 +105,7 @@ NS_GetCurrentThread(nsIThread** aResult)
 #endif
 }
 
-NS_METHOD
+nsresult
 NS_GetMainThread(nsIThread** aResult)
 {
 #ifdef MOZILLA_INTERNAL_API
@@ -135,7 +135,7 @@ NS_IsMainThread()
 }
 #endif
 
-NS_METHOD
+nsresult
 NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent)
 {
   nsresult rv;
@@ -168,14 +168,14 @@ NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent)
 // It is common to call NS_DispatchToCurrentThread with a newly
 // allocated runnable with a refcount of zero. To keep us from leaking
 // the runnable if the dispatch method fails, we take a death grip.
-NS_METHOD
+nsresult
 NS_DispatchToCurrentThread(nsIRunnable* aEvent)
 {
   nsCOMPtr<nsIRunnable> event(aEvent);
   return NS_DispatchToCurrentThread(event.forget());
 }
 
-NS_METHOD
+nsresult
 NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDispatchFlags)
 {
   LeakRefPtr<nsIRunnable> event(Move(aEvent));
@@ -195,7 +195,7 @@ NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDispat
 // likely that the runnable is being dispatched to the main thread
 // because it owns main thread only objects, so it is not safe to
 // release them here.
-NS_METHOD
+nsresult
 NS_DispatchToMainThread(nsIRunnable* aEvent, uint32_t aDispatchFlags)
 {
   nsCOMPtr<nsIRunnable> event(aEvent);
@@ -203,7 +203,7 @@ NS_DispatchToMainThread(nsIRunnable* aEvent, uint32_t aDispatchFlags)
 }
 
 #ifndef XPCOM_GLUE_AVOID_NSPR
-NS_METHOD
+nsresult
 NS_ProcessPendingEvents(nsIThread* aThread, PRIntervalTime aTimeout)
 {
   nsresult rv = NS_OK;
diff --git a/xpcom/glue/nsThreadUtils.h b/xpcom/glue/nsThreadUtils.h
index 4a5d1f113afc..2f2fad68f2e0 100644
--- a/xpcom/glue/nsThreadUtils.h
+++ b/xpcom/glue/nsThreadUtils.h
@@ -59,7 +59,7 @@ NS_SetThreadName(nsIThread* aThread, const char (&aName)[LEN])
  * @returns NS_ERROR_INVALID_ARG
  *   Indicates that the given name is not unique.
  */
-extern NS_METHOD
+extern nsresult
 NS_NewThread(nsIThread** aResult,
              nsIRunnable* aInitialEvent = nullptr,
              uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE);
@@ -68,7 +68,7 @@ NS_NewThread(nsIThread** aResult,
  * Creates a named thread, otherwise the same as NS_NewThread
  */
 template<size_t LEN>
-inline NS_METHOD
+inline nsresult
 NS_NewNamedThread(const char (&aName)[LEN],
                   nsIThread** aResult,
                   nsIRunnable* aInitialEvent = nullptr,
@@ -97,7 +97,7 @@ NS_NewNamedThread(const char (&aName)[LEN],
  * @param aResult
  *   The resulting nsIThread object.
  */
-extern NS_METHOD NS_GetCurrentThread(nsIThread** aResult);
+extern nsresult NS_GetCurrentThread(nsIThread** aResult);
 
 /**
  * Dispatch the given event to the current thread.
@@ -108,8 +108,8 @@ extern NS_METHOD NS_GetCurrentThread(nsIThread** aResult);
  * @returns NS_ERROR_INVALID_ARG
  *   If event is null.
  */
-extern NS_METHOD NS_DispatchToCurrentThread(nsIRunnable* aEvent);
-extern NS_METHOD
+extern nsresult NS_DispatchToCurrentThread(nsIRunnable* aEvent);
+extern nsresult
 NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent);
 
 /**
@@ -123,10 +123,10 @@ NS_DispatchToCurrentThread(already_AddRefed<nsIRunnable>&& aEvent);
  * @returns NS_ERROR_INVALID_ARG
  *   If event is null.
  */
-extern NS_METHOD
+extern nsresult
 NS_DispatchToMainThread(nsIRunnable* aEvent,
                         uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
-extern NS_METHOD
+extern nsresult
 NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent,
                         uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
 
@@ -146,7 +146,7 @@ NS_DispatchToMainThread(already_AddRefed<nsIRunnable>&& aEvent,
  *   value is simply used to determine whether or not to process another event.
  *   Pass PR_INTERVAL_NO_TIMEOUT to specify no timeout.
  */
-extern NS_METHOD
+extern nsresult
 NS_ProcessPendingEvents(nsIThread* aThread,
                         PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT);
 #endif