diff --git a/gfx/layers/ipc/AsyncPanZoomController.cpp b/gfx/layers/ipc/AsyncPanZoomController.cpp
index 7ef413bc4523..bf7f69b3d9da 100644
--- a/gfx/layers/ipc/AsyncPanZoomController.cpp
+++ b/gfx/layers/ipc/AsyncPanZoomController.cpp
@@ -393,7 +393,7 @@ AsyncPanZoomController::AsyncPanZoomController(uint64_t aLayersId,
      mTouchListenerTimeoutTask(nullptr),
      mX(MOZ_THIS_IN_INITIALIZER_LIST()),
      mY(MOZ_THIS_IN_INITIALIZER_LIST()),
-     mZoomConstraints(true, MIN_ZOOM, MAX_ZOOM),
+     mZoomConstraints(false, MIN_ZOOM, MAX_ZOOM),
      mLastSampleTime(GetFrameTime()),
      mState(NOTHING),
      mLastAsyncScrollTime(GetFrameTime()),
@@ -1643,6 +1643,8 @@ void AsyncPanZoomController::TimeoutTouchListeners() {
 }
 
 void AsyncPanZoomController::UpdateZoomConstraints(const ZoomConstraints& aConstraints) {
+  APZC_LOG("%p updating zoom constraints to %d %f %f\n", this, aConstraints.mAllowZoom,
+    aConstraints.mMinZoom.scale, aConstraints.mMaxZoom.scale);
   mZoomConstraints.mAllowZoom = aConstraints.mAllowZoom;
   mZoomConstraints.mMinZoom = (MIN_ZOOM > aConstraints.mMinZoom ? MIN_ZOOM : aConstraints.mMinZoom);
   mZoomConstraints.mMaxZoom = (MAX_ZOOM > aConstraints.mMaxZoom ? aConstraints.mMaxZoom : MAX_ZOOM);
diff --git a/widget/windows/winrt/APZController.cpp b/widget/windows/winrt/APZController.cpp
index 4d8518bfa87a..8fd4afb181d1 100644
--- a/widget/windows/winrt/APZController.cpp
+++ b/widget/windows/winrt/APZController.cpp
@@ -266,6 +266,20 @@ APZController::PostDelayedTask(Task* aTask, int aDelayMs)
   MessageLoop::current()->PostDelayedTask(FROM_HERE, aTask, aDelayMs);
 }
 
+bool
+APZController::GetRootZoomConstraints(ZoomConstraints* aOutConstraints)
+{
+  if (aOutConstraints) {
+    // Until we support the meta-viewport tag properly allow zooming
+    // from 1/4 to 4x by default.
+    aOutConstraints->mAllowZoom = true;
+    aOutConstraints->mMinZoom = CSSToScreenScale(0.25f);
+    aOutConstraints->mMaxZoom = CSSToScreenScale(4.0f);
+    return true;
+  }
+  return false;
+}
+
 // apzc notifications
 
 class TransformedStartEvent : public nsRunnable
diff --git a/widget/windows/winrt/APZController.h b/widget/windows/winrt/APZController.h
index 418e251db8cf..e1afda2456d1 100644
--- a/widget/windows/winrt/APZController.h
+++ b/widget/windows/winrt/APZController.h
@@ -23,6 +23,7 @@ class APZController :
 {
   typedef mozilla::layers::FrameMetrics FrameMetrics;
   typedef mozilla::layers::ScrollableLayerGuid ScrollableLayerGuid;
+  typedef mozilla::layers::ZoomConstraints ZoomConstraints;
 
 public:
   APZController() :
@@ -38,6 +39,7 @@ public:
   virtual void HandleLongTapUp(const mozilla::CSSIntPoint& aPoint, int32_t aModifiers);
   virtual void SendAsyncScrollDOMEvent(bool aIsRoot, const mozilla::CSSRect &aContentRect, const mozilla::CSSSize &aScrollableSize);
   virtual void PostDelayedTask(Task* aTask, int aDelayMs);
+  virtual bool GetRootZoomConstraints(ZoomConstraints* aOutConstraints);
   virtual void NotifyTransformBegin(const ScrollableLayerGuid& aGuid);
   virtual void NotifyTransformEnd(const ScrollableLayerGuid& aGuid);