--- a/dom/vr/VRServiceTest.cpp
+++ b/dom/vr/VRServiceTest.cpp
@@ -25,16 +25,17 @@ NS_INTERFACE_MAP_END_INHERITING(DOMEvent
 
 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())
 {
+  mSensorState.Clear();
   mDisplayInfo.mDisplayName = aID;
   mDisplayInfo.mType = VRDeviceType::Puppet;
   mDisplayInfo.mIsConnected = true;
   mDisplayInfo.mIsMounted = false;
   mDisplayInfo.mCapabilityFlags = VRDisplayCapabilityFlags::Cap_None |
                                   VRDisplayCapabilityFlags::Cap_Orientation |
                                   VRDisplayCapabilityFlags::Cap_AngularAcceleration |
                                   VRDisplayCapabilityFlags::Cap_Position |