diff --git a/src/fiber/execution_context/parallel/scheduler.cr b/src/fiber/execution_context/parallel/scheduler.cr
index b71c48279e19..48c48c26a251 100644
--- a/src/fiber/execution_context/parallel/scheduler.cr
+++ b/src/fiber/execution_context/parallel/scheduler.cr
@@ -155,6 +155,7 @@ module Fiber::ExecutionContext
         end
       ensure
         @event_loop.unregister(self)
+        ExecutionContext.thread_pool.checkin
       end
 
       private def find_next_runnable : Fiber?