diff --git a/image/DecodePool.cpp b/image/DecodePool.cpp
index d5ac056556d..5e53350ae31 100644
--- a/image/DecodePool.cpp
+++ b/image/DecodePool.cpp
@@ -237,6 +237,10 @@ public:
         return work;
       }
 
+#ifdef MOZ_NUWA_PROCESS
+      nsThreadManager::get()->SetThreadIdle(nullptr);
+#endif // MOZ_NUWA_PROCESS
+
       // Nothing to do; block until some work is available.
       mMonitor.Wait();
     } while (true);
@@ -252,6 +256,10 @@ private:
     work.mDecoder = aQueue.ElementAt(0);
     aQueue.RemoveElementAt(0);
 
+#ifdef MOZ_NUWA_PROCESS
+    nsThreadManager::get()->SetThreadWorking();
+#endif // MOZ_NUWA_PROCESS
+
     return work;
   }