--- a/dom/vr/VRServiceTest.cpp
+++ b/dom/vr/VRServiceTest.cpp
@@ -23,16 +23,17 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(VRMockDisplay)
 NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
 
 NS_IMPL_ADDREF_INHERITED(VRMockDisplay, DOMEventTargetHelper)
 NS_IMPL_RELEASE_INHERITED(VRMockDisplay, DOMEventTargetHelper)
 
 VRMockDisplay::VRMockDisplay(const nsCString& aID, uint32_t aDeviceID)
  : mDeviceID(aDeviceID)
+ , mTimestamp(TimeStamp::Now())
 {
   mDisplayInfo.mDisplayName = aID;
   mDisplayInfo.mType = VRDeviceType::Puppet;
   mDisplayInfo.mIsConnected = true;
   mDisplayInfo.mIsMounted = false;
   mDisplayInfo.mCapabilityFlags = VRDisplayCapabilityFlags::Cap_None |
                                   VRDisplayCapabilityFlags::Cap_Orientation |
                                   VRDisplayCapabilityFlags::Cap_AngularAcceleration |
@@ -73,17 +74,17 @@ void
 VRMockDisplay::SetPose(const Nullable<Float32Array>& aPosition,
                        const Nullable<Float32Array>& aLinearVelocity,
                        const Nullable<Float32Array>& aLinearAcceleration,
                        const Nullable<Float32Array>& aOrientation,
                        const Nullable<Float32Array>& aAngularVelocity,
                        const Nullable<Float32Array>& aAngularAcceleration)
 {
   mSensorState.Clear();
-  mSensorState.timestamp = PR_Now();
+  mSensorState.timestamp = (TimeStamp::Now() - mTimestamp).ToSeconds();
   mSensorState.flags = VRDisplayCapabilityFlags::Cap_Orientation |
                        VRDisplayCapabilityFlags::Cap_Position |
                        VRDisplayCapabilityFlags::Cap_AngularAcceleration |
                        VRDisplayCapabilityFlags::Cap_LinearAcceleration |
                        VRDisplayCapabilityFlags::Cap_External |
                        VRDisplayCapabilityFlags::Cap_MountDetection |
                        VRDisplayCapabilityFlags::Cap_Present;
 

--- a/dom/vr/VRServiceTest.h
+++ b/dom/vr/VRServiceTest.h
@@ -31,16 +31,17 @@ public:
   virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
 
 private:
   ~VRMockDisplay() = default;
 
   uint32_t mDeviceID;
   gfx::VRDisplayInfo mDisplayInfo;
   gfx::VRHMDSensorState mSensorState;
+  TimeStamp mTimestamp;
 };
 
 class VRMockController : public DOMEventTargetHelper
 {
 public:
   NS_DECL_ISUPPORTS_INHERITED
   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(VRMockController, DOMEventTargetHelper)
 

--- a/gfx/vr/gfxVRPuppet.cpp
+++ b/gfx/vr/gfxVRPuppet.cpp
@@ -84,17 +84,16 @@ VRDisplayPuppet::VRDisplayPuppet()
   mDisplayInfo.mSittingToStandingTransform._33 = 1.0f;
   mDisplayInfo.mSittingToStandingTransform._34 = 0.0f;
 
   mDisplayInfo.mSittingToStandingTransform._41 = 0.0f;
   mDisplayInfo.mSittingToStandingTransform._42 = 0.75f;
   mDisplayInfo.mSittingToStandingTransform._43 = 0.0f;
 
   mSensorState.Clear();
-  mSensorState.timestamp = PR_Now();
 
   gfx::Quaternion rot;
 
   mSensorState.flags |= VRDisplayCapabilityFlags::Cap_Orientation;
   mSensorState.orientation[0] = rot.x;
   mSensorState.orientation[1] = rot.y;
   mSensorState.orientation[2] = rot.z;
   mSensorState.orientation[3] = rot.w;