diff --git a/poseidon/static/fiber_scheduler.hpp b/poseidon/static/fiber_scheduler.hpp
index 700b7ea2..4e685a15 100644
--- a/poseidon/static/fiber_scheduler.hpp
+++ b/poseidon/static/fiber_scheduler.hpp
@@ -68,7 +68,7 @@ class Fiber_Scheduler
     // is not zero, it specifies the maximum timeout that the current fiber
     // can be suspended.
     void
-    yield(const Abstract_Fiber& tfiber, shptrR<Abstract_Future> futr_opt, milliseconds fail_timeout_override);
+    yield(const Abstract_Fiber& tfiber, shptrR<Abstract_Future> futr_opt, milliseconds fail_timeout_override = 0s);
   };
 
 }  // namespace poseidon