diff --git a/HISTORY.rst b/HISTORY.rst
index 33903908..af35a198 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -17,6 +17,8 @@ PlatformIO 2.0
   the size of a credit card
 * Check program size before uploading to the board
   (`issue #689 <https://github.com/platformio/platformio/issues/689>`_)
+* Improved firmware uploading to Arduino Leonardo based boards
+  (`issue #691 <https://github.com/platformio/platformio/issues/691>`_)
 * Fixed issue with ``-L relative/path`` when parsing ``build_flags``
   (`issue #688 <https://github.com/platformio/platformio/issues/688>`_)
 
diff --git a/platformio/builder/tools/pioupload.py b/platformio/builder/tools/pioupload.py
index ccc4d625..874d4086 100644
--- a/platformio/builder/tools/pioupload.py
+++ b/platformio/builder/tools/pioupload.py
@@ -54,6 +54,7 @@ def WaitForNewSerialPort(env, before):
     prev_port = env.subst("$UPLOAD_PORT")
     new_port = None
     elapsed = 0
+    sleep(1)
     while elapsed < 5 and new_port is None:
         now = util.get_serialports()
         for p in now: