diff --git a/Base/res/html/misc/unhandledpromisetest.html b/Base/res/html/misc/unhandledpromisetest.html
new file mode 100644
index 0000000000..3838ff17dc
--- /dev/null
+++ b/Base/res/html/misc/unhandledpromisetest.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Unhandled Promise rejection with no [[ScriptOrModule]] for the current execution context</title>
+</head>
+<body>
+  <button onclick="
+    Promise.reject(new Error('Success!'));
+    window.timer = setTimeout(() => {
+      const element = document.createElement('p');
+      element.innerText = 'Did not receieve unhandledrejection event in 100ms.';
+      element.style.color = 'red';
+      document.body.appendChild(element);
+    }, 100)
+  ">
+    Click me to cause an unhandled promise rejection.
+  </button>
+
+  <script>
+    window.onunhandledrejection = (rejectionEvent) => {
+      clearTimeout(window.timer);
+      const element = document.createElement("p");
+      element.innerText = rejectionEvent.reason.message;
+      element.style.color = "green";
+      document.body.appendChild(element);
+    }
+  </script>
+</body>
+</html>
diff --git a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
index e1209646bb..9329b77ea6 100644
--- a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
+++ b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
@@ -55,8 +55,7 @@ JS::VM& main_thread_vm()
         vm->host_promise_rejection_tracker = [](JS::Promise& promise, JS::Promise::RejectionOperation operation) {
             // 1. Let script be the running script.
             //    The running script is the script in the [[HostDefined]] field in the ScriptOrModule component of the running JavaScript execution context.
-            // FIXME: This currently assumes there's only a ClassicScript.
-            HTML::ClassicScript* script { nullptr };
+            HTML::Script* script { nullptr };
             vm->running_execution_context().script_or_module.visit(
                 [&script](WeakPtr<JS::Script>& js_script) {
                     script = verify_cast<HTML::ClassicScript>(js_script->host_defined());
@@ -67,19 +66,17 @@ JS::VM& main_thread_vm()
                 [](Empty) {
                 });
 
-            // If there's no script, we're out of luck. Return.
-            // FIXME: This can happen from JS::NativeFunction, which makes its callee contexts [[ScriptOrModule]] null.
-            if (!script) {
-                dbgln("FIXME: Unable to process unhandled promise rejection in host_promise_rejection_tracker as the running script is null.");
-                return;
+            // 2. If script is a classic script and script's muted errors is true, then return.
+            // NOTE: is<T>() returns false if nullptr is passed.
+            if (is<HTML::ClassicScript>(script)) {
+                auto const& classic_script = static_cast<HTML::ClassicScript const&>(*script);
+                if (classic_script.muted_errors() == HTML::ClassicScript::MutedErrors::Yes)
+                    return;
             }
 
-            // 2. If script's muted errors is true, terminate these steps.
-            if (script->muted_errors() == HTML::ClassicScript::MutedErrors::Yes)
-                return;
-
-            // 3. Let settings object be script's settings object.
-            auto& settings_object = script->settings_object();
+            // 3. Let settings object be the current settings object.
+            // 4. If script is not null, then set settings object to script's settings object.
+            auto& settings_object = script ? script->settings_object() : HTML::current_settings_object();
 
             switch (operation) {
             case JS::Promise::RejectionOperation::Reject:
