diff -r 6ced540a92bc Modules/posixmodule.c
--- a/Modules/posixmodule.c	Wed Dec 21 14:08:55 2016 +0200
+++ b/Modules/posixmodule.c	Wed Dec 21 17:23:11 2016 +0200
@@ -846,7 +846,7 @@ static int
 path_converter(PyObject *o, void *p)
 {
     path_t *path = (path_t *)p;
-    PyObject *bytes, *to_cleanup = NULL;
+    PyObject *bytes = NULL, *to_cleanup = NULL;
     Py_ssize_t length;
     int is_index, is_buffer, is_bytes, is_unicode;
     /* Default to failure, forcing explicit signaling of succcess. */
@@ -1002,7 +1002,6 @@ path_converter(PyObject *o, void *p)
     narrow = PyBytes_AS_STRING(bytes);
     if ((size_t)length != strlen(narrow)) {
         FORMAT_EXCEPTION(PyExc_ValueError, "embedded null character in %s");
-        Py_DECREF(bytes);
         goto exit;
     }
 
@@ -1039,14 +1038,15 @@ path_converter(PyObject *o, void *p)
     path->object = o;
     path->fd = -1;
     if (bytes == o) {
-        Py_DECREF(bytes);
         ret = 1;
     }
     else {
         path->cleanup = bytes;
+        bytes = NULL;
         ret = Py_CLEANUP_SUPPORTED;
     }
  exit:
+    Py_XDECREF(bytes);
     Py_XDECREF(to_cleanup);
     return ret;
 }