diff --git a/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp b/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp
index 5c56ea0161..b8611a25e0 100644
--- a/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp
+++ b/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp
@@ -331,6 +331,10 @@ ExecuteScriptResultSerialized execute_async_script(Web::Page& page, DeprecatedSt
     auto& vm = window->vm();
     auto start = MonotonicTime::now();
 
+    auto has_timed_out = [&] {
+        return timeout.has_value() && (MonotonicTime::now() - start) > Duration::from_seconds(static_cast<i64>(*timeout));
+    };
+
     // AD-HOC: An execution context is required for Promise creation hooks.
     HTML::TemporaryExecutionContext execution_context { document->relevant_settings_object() };
 
@@ -381,7 +385,7 @@ ExecuteScriptResultSerialized execute_async_script(Web::Page& page, DeprecatedSt
         vm.custom_data()->spin_event_loop_until([&] {
             if (script_promise.state() != JS::Promise::State::Pending)
                 return true;
-            if (timeout.has_value() && (MonotonicTime::now() - start) > Duration::from_seconds(static_cast<i64>(*timeout)))
+            if (has_timed_out())
                 return true;
             return false;
         });
@@ -395,12 +399,22 @@ ExecuteScriptResultSerialized execute_async_script(Web::Page& page, DeprecatedSt
             WebIDL::reject_promise(realm, promise_capability, script_promise.result());
     }();
 
-    // FIXME: 6. If promise is still pending and session script timeout milliseconds is reached, return error with error code script timeout.
-
+    // 6. If promise is still pending and session script timeout milliseconds is reached, return error with error code script timeout.
     vm.custom_data()->spin_event_loop_until([&] {
+        if (has_timed_out()) {
+            return true;
+        }
+
         return promise->state() != JS::Promise::State::Pending;
     });
 
+    if (has_timed_out()) {
+        auto error_object = JsonObject {};
+        error_object.set("name", "Error");
+        error_object.set("message", "script timeout");
+        return { ExecuteScriptResultType::Timeout, move(error_object) };
+    }
+
     auto json_value_or_error = json_clone(realm, promise->result());
     if (json_value_or_error.is_error()) {
         auto error_object = JsonObject {};