diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index eda8d6f8b4c..21785498be6 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -182,6 +182,12 @@ pub extern "C" fn Servo_Initialize(dummy_url_data: *mut URLExtraData) {
     unsafe { DUMMY_URL_DATA = dummy_url_data; }
 }
 
+#[no_mangle]
+pub extern "C" fn Servo_InitializeCooperativeThread() {
+    // Pretend that we're a Servo Layout thread to make some assertions happy.
+    thread_state::initialize(thread_state::LAYOUT);
+}
+
 #[no_mangle]
 pub extern "C" fn Servo_Shutdown() {
     // The dummy url will be released after shutdown, so clear the