diff --git a/gfx/layers/ipc/ImageBridgeChild.cpp b/gfx/layers/ipc/ImageBridgeChild.cpp
index c8abcff401a..f8cbe127d11 100644
--- a/gfx/layers/ipc/ImageBridgeChild.cpp
+++ b/gfx/layers/ipc/ImageBridgeChild.cpp
@@ -221,7 +221,6 @@ static void ImageBridgeShutdownStep2(ReentrantMonitor *aBarrier, bool *aDone)
 
   sImageBridgeChildSingleton->SendStop();
 
-  sImageBridgeChildSingleton = nullptr;
   *aDone = true;
   aBarrier->NotifyAll();
 }
@@ -248,10 +247,14 @@ static void ConnectImageBridge(ImageBridgeChild * child, ImageBridgeParent * par
 ImageBridgeChild::ImageBridgeChild()
   : mShuttingDown(false)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   mTxn = new CompositableTransaction();
 }
 ImageBridgeChild::~ImageBridgeChild()
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   delete mTxn;
 }
 
@@ -547,7 +550,7 @@ PImageBridgeChild*
 ImageBridgeChild::StartUpInChildProcess(Transport* aTransport,
                                         ProcessId aOtherProcess)
 {
-  NS_ASSERTION(NS_IsMainThread(), "Should be on the main Thread!");
+  MOZ_ASSERT(NS_IsMainThread());
 
   gfxPlatform::GetPlatform();
 
@@ -572,7 +575,7 @@ ImageBridgeChild::StartUpInChildProcess(Transport* aTransport,
 
 void ImageBridgeChild::ShutDown()
 {
-  MOZ_ASSERT(NS_IsMainThread(), "Should be on the main Thread!");
+  MOZ_ASSERT(NS_IsMainThread());
   if (ImageBridgeChild::IsCreated()) {
     MOZ_ASSERT(!sImageBridgeChildSingleton->mShuttingDown);
 
@@ -600,6 +603,8 @@ void ImageBridgeChild::ShutDown()
       }
     }
 
+    sImageBridgeChildSingleton = nullptr;
+
     delete sImageBridgeChildThread;
     sImageBridgeChildThread = nullptr;
   }
diff --git a/gfx/layers/ipc/ImageBridgeParent.cpp b/gfx/layers/ipc/ImageBridgeParent.cpp
index 40920d559c2..fceed182b4c 100644
--- a/gfx/layers/ipc/ImageBridgeParent.cpp
+++ b/gfx/layers/ipc/ImageBridgeParent.cpp
@@ -51,6 +51,8 @@ ImageBridgeParent::ImageBridgeParent(MessageLoop* aLoop,
   , mTransport(aTransport)
   , mChildProcessId(aChildProcessId)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   // creates the map only if it has not been created already, so it is safe
   // with several bridges
   CompositableMap::Create();
@@ -59,10 +61,14 @@ ImageBridgeParent::ImageBridgeParent(MessageLoop* aLoop,
 
 ImageBridgeParent::~ImageBridgeParent()
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   if (mTransport) {
+    MOZ_ASSERT(XRE_GetIOMessageLoop());
     XRE_GetIOMessageLoop()->PostTask(FROM_HERE,
                                      new DeleteTask<Transport>(mTransport));
   }
+
   sImageBridges.erase(mChildProcessId);
 }