diff --git a/Lib/asyncio/base_subprocess.py b/Lib/asyncio/base_subprocess.py
index 08080bd7012..8fc253c18eb 100644
--- a/Lib/asyncio/base_subprocess.py
+++ b/Lib/asyncio/base_subprocess.py
@@ -210,6 +210,10 @@ def _process_exited(self, returncode):
             logger.info('%r exited with return code %r',
                         self, returncode)
         self._returncode = returncode
+        if self._proc.returncode is None:
+            # asyncio uses a child watcher: copy the status into the Popen
+            # object. On Python 3.6, it is required to avoid a ResourceWarning.
+            self._proc.returncode = returncode
         self._call(self._protocol.process_exited)
         self._try_finish()