--- a/media/mtransport/transportflow.cpp
+++ b/media/mtransport/transportflow.cpp
@@ -30,20 +30,22 @@ TransportFlow::~TransportFlow() {
 
   // Push the destruction onto the STS thread. Note that there
   // is still some possibility that someone is accessing this
   // object simultaneously, but as long as smart pointer discipline
   // is maintained, it shouldn't be possible to access and
   // destroy it simultaneously. The conversion to an nsAutoPtr
   // ensures automatic destruction of the queue at exit of
   // DestroyFinal.
-  nsAutoPtr<std::deque<TransportLayer*>> layers_tmp(layers_.release());
-  RUN_ON_THREAD(target_,
-                WrapRunnableNM(&TransportFlow::DestroyFinal, layers_tmp),
-                NS_DISPATCH_NORMAL);
+  if (target_) {
+    nsAutoPtr<std::deque<TransportLayer*>> layers_tmp(layers_.release());
+    RUN_ON_THREAD(target_,
+                  WrapRunnableNM(&TransportFlow::DestroyFinal, layers_tmp),
+                  NS_DISPATCH_NORMAL);
+  }
 }
 
 void TransportFlow::DestroyFinal(nsAutoPtr<std::deque<TransportLayer *> > layers) {
   ClearLayers(layers.get());
 }
 
 void TransportFlow::ClearLayers(std::queue<TransportLayer *>* layers) {
   while (!layers->empty()) {