diff --git a/test/fiber/test_sleep.rb b/test/fiber/test_sleep.rb
index 844369740f..a7e88c0367 100644
--- a/test/fiber/test_sleep.rb
+++ b/test/fiber/test_sleep.rb
@@ -59,6 +59,9 @@ class TestFiberSleep < Test::Unit::TestCase
       Fiber.schedule do
         sleep 0
       end
+
+    ensure
+      scheduler.close
     end
 
     assert_raise(RuntimeError) do
diff --git a/test/fiber/test_thread.rb b/test/fiber/test_thread.rb
index b7323d7237..7221f767ac 100644
--- a/test/fiber/test_thread.rb
+++ b/test/fiber/test_thread.rb
@@ -56,6 +56,8 @@ class TestFiberThread < Test::Unit::TestCase
       end
 
       scheduler.run
+    ensure
+      scheduler.close
     end
 
     assert_raise(RuntimeError) do