diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 822ddb459e2615..0db6571f291dae 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -986,7 +986,7 @@ def _execute_child(self, args, executable, preexec_fn, close_fds,
                                          int(not close_fds),
                                          creationflags,
                                          env,
-                                         cwd,
+                                         os.fspath(cwd) if cwd is not None else None,
                                          startupinfo)
             finally:
                 # Child is launched. Close the parent's copy of those pipe