diff --git a/dom/webgpu/Device.cpp b/dom/webgpu/Device.cpp
index fb5521e4b3eb..d87b1990a594 100644
--- a/dom/webgpu/Device.cpp
+++ b/dom/webgpu/Device.cpp
@@ -79,7 +79,8 @@ void Device::Cleanup() {
     mBridge->UnregisterDevice(mId);
   }
 
-  if (mLostPromise) {
+  // Cycle collection may have disconnected the promise object.
+  if (mLostPromise && mLostPromise->PromiseObj() != nullptr) {
     auto info = MakeRefPtr<DeviceLostInfo>(GetParentObject(),
                                            dom::GPUDeviceLostReason::Destroyed,
                                            u"Device destroyed"_ns);