diff --git a/components/script/timers.rs b/components/script/timers.rs
index 53113e06682..504dbb8aaaf 100644
--- a/components/script/timers.rs
+++ b/components/script/timers.rs
@@ -176,7 +176,10 @@ impl OneshotTimers {
         let base_time = self.base_time();
 
         // Since the event id was the expected one, at least one timer should be due.
-        assert!(base_time >= self.timers.borrow().last().unwrap().scheduled_for);
+        if base_time < self.timers.borrow().last().unwrap().scheduled_for {
+            warn!("Unexpected timing!");
+            return;
+        }
 
         // select timers to run to prevent firing timers
         // that were installed during fire of another timer