diff --git a/Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp b/Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp
index af711d4c831..8ce8c2936d4 100644
--- a/Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp
+++ b/Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp
@@ -473,6 +473,10 @@ void perform_a_microtask_checkpoint()
 // https://html.spec.whatwg.org/#perform-a-microtask-checkpoint
 void EventLoop::perform_a_microtask_checkpoint()
 {
+    // NOTE: This assertion is per requirement 9.5 of the ECMA-262 spec, see: https://tc39.es/ecma262/#sec-jobs
+    // > At some future point in time, when there is no running context in the agent for which the job is scheduled and that agent's execution context stack is empty...
+    VERIFY(vm().execution_context_stack().is_empty());
+
     // 1. If the event loop's performing a microtask checkpoint is true, then return.
     if (m_performing_a_microtask_checkpoint)
         return;