diff --git a/uasyncio.core/uasyncio/core.py b/uasyncio.core/uasyncio/core.py
index 3071ce2a..dbfc9106 100644
--- a/uasyncio.core/uasyncio/core.py
+++ b/uasyncio.core/uasyncio/core.py
@@ -94,8 +94,6 @@ class EventLoop:
                         log.debug("Coroutine %s yield result: %s", cb, ret)
                     if isinstance(ret, SysCall1):
                         arg = ret.arg
-                        if isinstance(ret, Sleep):
-                            delay = int(arg * 1000)
                         if isinstance(ret, SleepMs):
                             delay = arg
                         elif isinstance(ret, IORead):
@@ -153,9 +151,6 @@ class SysCall1(SysCall):
     def __init__(self, arg):
         self.arg = arg
 
-class Sleep(SysCall1):
-    pass
-
 class StopLoop(SysCall1):
     pass