--- a/gfx/vr/gfxVROculus.cpp
+++ b/gfx/vr/gfxVROculus.cpp
@@ -1742,17 +1742,18 @@ VRSystemManagerOculus::VibrateHaptic(uin
   controller->VibrateHaptic(mSession->Get(), aHapticIndex, aIntensity, aDuration, aPromiseID);
 }
 
 void
 VRSystemManagerOculus::StopVibrateHaptic(uint32_t aControllerIdx)
 {
   // The session is available after VRDisplay is created
   // at GetHMDs().
-  if (!mSession || !mSession->IsTrackingReady()) {
+  if (!mSession || !mSession->IsTrackingReady() ||
+      (aControllerIdx >= mOculusController.Length())) {
     return;
   }
 
   RefPtr<impl::VRControllerOculus> controller = mOculusController[aControllerIdx];
   MOZ_ASSERT(controller);
 
   controller->StopVibrateHaptic();
 }

--- a/gfx/vr/gfxVROpenVR.cpp
+++ b/gfx/vr/gfxVROpenVR.cpp
@@ -942,17 +942,17 @@ VRSystemManagerOpenVR::VibrateHaptic(uin
   controller->VibrateHaptic(mVRSystem, aHapticIndex, aIntensity, aDuration, aPromiseID);
 }
 
 void
 VRSystemManagerOpenVR::StopVibrateHaptic(uint32_t aControllerIdx)
 {
   // mVRSystem is available after VRDisplay is created
   // at GetHMDs().
-  if (!mVRSystem) {
+  if (!mVRSystem || (aControllerIdx >= mOpenVRController.Length())) {
     return;
   }
 
   RefPtr<impl::VRControllerOpenVR> controller = mOpenVRController[aControllerIdx];
   MOZ_ASSERT(controller);
 
   controller->StopVibrateHaptic();
 }