diff --git a/components/style/thread_state.rs b/components/style/thread_state.rs
index 894cdb4a813..d06f47aabe4 100644
--- a/components/style/thread_state.rs
+++ b/components/style/thread_state.rs
@@ -53,7 +53,9 @@ thread_local!(static STATE: RefCell<Option<ThreadState>> = RefCell::new(None));
 pub fn initialize(x: ThreadState) {
     STATE.with(|ref k| {
         if let Some(ref s) = *k.borrow() {
-            panic!("Thread state already initialized as {:?}", s);
+            if x != *s {
+                panic!("Thread state already initialized as {:?}", s);
+            }
         }
         *k.borrow_mut() = Some(x);
     });