diff --git a/source/drivers/MicroBitSerial.cpp b/source/drivers/MicroBitSerial.cpp
index 7fad4e00..198caba4 100644
--- a/source/drivers/MicroBitSerial.cpp
+++ b/source/drivers/MicroBitSerial.cpp
@@ -295,7 +295,7 @@ void MicroBitSerial::send(MicroBitSerialMode mode)
         while(txBufferedSize() > 0);
 
     if(mode == SYNC_SLEEP)
-        fiber_sleep(0);
+        schedule();
 }
 
 /**