diff --git a/dom/messagechannel/MessagePortParent.h b/dom/messagechannel/MessagePortParent.h
index 4cbebe29b..23195c3a7 100644
--- a/dom/messagechannel/MessagePortParent.h
+++ b/dom/messagechannel/MessagePortParent.h
@@ -5,6 +5,7 @@
 #ifndef mozilla_dom_MessagePortParent_h
 #define mozilla_dom_MessagePortParent_h
 
+#include "mozilla/WeakPtr.h"
 #include "mozilla/dom/PMessagePortParent.h"
 
 namespace mozilla {
@@ -12,7 +13,8 @@ namespace dom {
 
 class MessagePortService;
 
-class MessagePortParent final : public PMessagePortParent
+class MessagePortParent final : public PMessagePortParent,
+                                public SupportsWeakPtr<MessagePortParent>
 {
 public:
   explicit MessagePortParent(const nsID& aUUID);
@@ -40,6 +42,8 @@ public:
                          const nsID& aDestinationUUID,
                          const uint32_t& aSequenceID);
 
+  MOZ_DECLARE_WEAKREFERENCE_TYPENAME(MessagePortParent)
+  
 private:
   virtual bool RecvPostMessages(nsTArray<MessagePortMessage>&& aMessages)
                                                                        override;
diff --git a/dom/messagechannel/MessagePortService.cpp b/dom/messagechannel/MessagePortService.cpp
index c76d9382b..85d0d42e9 100644
--- a/dom/messagechannel/MessagePortService.cpp
+++ b/dom/messagechannel/MessagePortService.cpp
@@ -9,6 +9,7 @@
 #include "mozilla/ipc/BackgroundParent.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/Unused.h"
+#include "mozilla/WeakPtr.h"
 #include "nsTArray.h"
 
 using mozilla::ipc::AssertIsOnBackgroundThread;
@@ -59,7 +60,7 @@ public:
   {
     uint32_t mSequenceID;
     // MessagePortParent keeps the service alive, and we don't want a cycle.
-    MessagePortParent* mParent;
+    WeakPtr<MessagePortParent> mParent;
   };
 
   FallibleTArray<NextParent> mNextParents;
@@ -275,9 +276,13 @@ MessagePortService::CloseAll(const nsID& aUUID, bool aForced)
     data->mParent->Close();
   }
 
-  for (const MessagePortServiceData::NextParent& parent : data->mNextParents) {
-    parent.mParent->CloseAndDelete();
+  for (const MessagePortServiceData::NextParent& nextParent : data->mNextParents) {
+    MessagePortParent* const parent = nextParent.mParent;
+    if (parent) {
+      parent->CloseAndDelete();
+    }
   }
+  data->mNextParents.Clear();
 
   nsID destinationUUID = data->mDestinationUUID;