diff --git a/test/scheduler.rb b/test/scheduler.rb
index a9cf7a91..204a2971 100644
--- a/test/scheduler.rb
+++ b/test/scheduler.rb
@@ -14,6 +14,14 @@
 end
 
 class Scheduler
+  experimental = Warning[:experimental]
+  begin
+    Warning[:experimental] = false
+    IO::Buffer.new(0)
+  ensure
+    Warning[:experimental] = experimental
+  end
+
   def initialize
     @readable = {}
     @writable = {}
@@ -199,6 +207,7 @@ def io_select(...)
   # Used for Kernel#sleep and Thread::Mutex#sleep
   def kernel_sleep(duration = nil)
     # $stderr.puts [__method__, duration, Fiber.current].inspect
+
     self.block(:sleep, duration)
 
     return true