diff --git a/dom/system/gonk/Volume.cpp b/dom/system/gonk/Volume.cpp
index d5976c906806..cca366aabea6 100644
--- a/dom/system/gonk/Volume.cpp
+++ b/dom/system/gonk/Volume.cpp
@@ -65,6 +65,9 @@ Volume::Volume(const nsCSubstring& aName)
 void
 Volume::SetMediaPresent(bool aMediaPresent)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   // mMediaPresent is slightly redunant to the state, however
   // when media is removed (while Idle), we get the following:
   //    631 Volume sdcard /mnt/sdcard disk removed (179:0)
@@ -100,6 +103,9 @@ Volume::SetMediaPresent(bool aMediaPresent)
 void
 Volume::SetState(Volume::STATE aNewState)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   if (aNewState == mState) {
     return;
   }
@@ -127,6 +133,9 @@ Volume::SetState(Volume::STATE aNewState)
 void
 Volume::SetMountPoint(const nsCSubstring& aMountPoint)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   if (mMountPoint.Equals(aMountPoint)) {
     return;
   }
@@ -137,30 +146,45 @@ Volume::SetMountPoint(const nsCSubstring& aMountPoint)
 void
 Volume::StartMount(VolumeResponseCallback* aCallback)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   StartCommand(new VolumeActionCommand(this, "mount", "", aCallback));
 }
 
 void
 Volume::StartUnmount(VolumeResponseCallback* aCallback)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   StartCommand(new VolumeActionCommand(this, "unmount", "force", aCallback));
 }
 
 void
 Volume::StartShare(VolumeResponseCallback* aCallback)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   StartCommand(new VolumeActionCommand(this, "share", "ums", aCallback));
 }
 
 void
 Volume::StartUnshare(VolumeResponseCallback* aCallback)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   StartCommand(new VolumeActionCommand(this, "unshare", "ums", aCallback));
 }
 
 void
 Volume::StartCommand(VolumeCommand* aCommand)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   VolumeManager::PostCommand(aCommand);
 }
 
@@ -168,6 +192,7 @@ Volume::StartCommand(VolumeCommand* aCommand)
 void
 Volume::RegisterObserver(Volume::EventObserver* aObserver)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
   MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
 
   mEventObserverList.AddObserver(aObserver);
@@ -183,6 +208,7 @@ Volume::RegisterObserver(Volume::EventObserver* aObserver)
 void
 Volume::UnregisterObserver(Volume::EventObserver* aObserver)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
   MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
 
   mEventObserverList.RemoveObserver(aObserver);
@@ -194,6 +220,9 @@ Volume::UpdateMountLock(const nsACString& aVolumeName,
                         const int32_t& aMountGeneration,
                         const bool& aMountLocked)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   RefPtr<Volume> vol = VolumeManager::FindVolumeByName(aVolumeName);
   if (!vol || (vol->mMountGeneration != aMountGeneration)) {
     return;
@@ -208,6 +237,9 @@ Volume::UpdateMountLock(const nsACString& aVolumeName,
 void
 Volume::HandleVoldResponse(int aResponseCode, nsCWhitespaceTokenizer& aTokenizer)
 {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+  MOZ_ASSERT(MessageLoop::current() == XRE_GetIOMessageLoop());
+
   // The volume name will have already been parsed, and the tokenizer will point
   // to the token after the volume name
   switch (aResponseCode) {
diff --git a/dom/system/gonk/nsVolume.cpp b/dom/system/gonk/nsVolume.cpp
index ec9938920f48..a0eeefda9ec5 100644
--- a/dom/system/gonk/nsVolume.cpp
+++ b/dom/system/gonk/nsVolume.cpp
@@ -38,6 +38,11 @@ NS_VolumeStateStr(int32_t aState)
   return "???";
 }
 
+// While nsVolumes can only be used on the main thread, in the
+// UpdateVolumeRunnable constructor (which is called from IOThread) we
+// allocate an nsVolume which is then passed to MainThread. Since we
+// have a situation where we allocate on one thread and free on another
+// we use a thread safe AddRef implementation.
 NS_IMPL_THREADSAFE_ISUPPORTS1(nsVolume, nsIVolume)
 
 nsVolume::nsVolume(const Volume* aVolume)
@@ -106,6 +111,8 @@ nsVolume::LogState() const
 
 void nsVolume::Set(const nsVolume* aVolume)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   mName = aVolume->mName;
   mMountPoint = aVolume->mMountPoint;
   mState = aVolume->mState;
@@ -139,6 +146,8 @@ void nsVolume::Set(const nsVolume* aVolume)
 void
 nsVolume::UpdateMountLock(const nsAString& aMountLockState)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   // There are 3 states, unlocked, locked-background, and locked-foreground
   // I figured it was easier to use negtive logic and compare for unlocked.
   UpdateMountLock(!aMountLockState.EqualsLiteral("unlocked"));
@@ -147,6 +156,8 @@ nsVolume::UpdateMountLock(const nsAString& aMountLockState)
 void
 nsVolume::UpdateMountLock(bool aMountLocked)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   if (aMountLocked == mMountLocked) {
     return;
   }
diff --git a/toolkit/mozapps/update/updater/updater.cpp b/toolkit/mozapps/update/updater/updater.cpp
index 3c12874cf8a5..b1b0630ca031 100644
--- a/toolkit/mozapps/update/updater/updater.cpp
+++ b/toolkit/mozapps/update/updater/updater.cpp
@@ -2088,8 +2088,7 @@ ReadMARChannelIDs(const NS_tchar *path, MARChannelStringTable *results)
 static int
 GetUpdateFileName(NS_tchar *fileName, int maxChars)
 {
-#if defined(MOZ_WIDGET_GONK)
-  // If an update.link file exists, then it will contain the name
+#if defined(MOZ_WIDGET_GONK)  // If an update.link file exists, then it will contain the name
   // of the update file (terminated by a newline).
 
   NS_tchar linkFileName[MAXPATHLEN];