diff --git a/layout/base/nsRefreshDriver.cpp b/layout/base/nsRefreshDriver.cpp
index bc1a27852b..8a62b517e9 100644
--- a/layout/base/nsRefreshDriver.cpp
+++ b/layout/base/nsRefreshDriver.cpp
@@ -478,6 +478,9 @@ private:
 
     bool NotifyVsync(TimeStamp aVsyncTimestamp) override
     {
+      // IMPORTANT: All paths through this method MUST hold a strong ref on
+      // |this| for the duration of the TickRefreshDriver callback.
+
       if (!NS_IsMainThread()) {
         MOZ_ASSERT(XRE_IsParentProcess());
         // Compress vsync notifications such that only 1 may run at a time
@@ -498,6 +501,7 @@ private:
                                           aVsyncTimestamp);
         NS_DispatchToMainThread(vsyncEvent);
       } else {
+        RefPtr<RefreshDriverVsyncObserver> kungFuDeathGrip(this);
         TickRefreshDriver(aVsyncTimestamp);
       }