diff --git a/Lib/asyncio/unix_events.py b/Lib/asyncio/unix_events.py
index eb3fb9f91c0..80a98f806ef 100644
--- a/Lib/asyncio/unix_events.py
+++ b/Lib/asyncio/unix_events.py
@@ -160,9 +160,10 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
             transp = _UnixSubprocessTransport(self, protocol, args, shell,
                                               stdin, stdout, stderr, bufsize,
                                               extra=None, **kwargs)
+            yield from transp._post_init()
             watcher.add_child_handler(transp.get_pid(),
                                       self._child_watcher_callback, transp)
-        yield from transp._post_init()
+
         return transp
 
     def _child_watcher_callback(self, pid, returncode, transp):