diff --git a/extmod/vfs_posix_file.c b/extmod/vfs_posix_file.c
index 81a608d2b6..2f70789543 100644
--- a/extmod/vfs_posix_file.c
+++ b/extmod/vfs_posix_file.c
@@ -279,14 +279,14 @@ STATIC const mp_stream_p_t vfs_posix_textio_stream_p = {
 
 #if MICROPY_PY_SYS_STDIO_BUFFER
 
-const mp_obj_vfs_posix_file_t mp_sys_stdin_buffer_obj = {{&mp_type_vfs_posix_fileio}, STDIN_FILENO};
-const mp_obj_vfs_posix_file_t mp_sys_stdout_buffer_obj = {{&mp_type_vfs_posix_fileio}, STDOUT_FILENO};
-const mp_obj_vfs_posix_file_t mp_sys_stderr_buffer_obj = {{&mp_type_vfs_posix_fileio}, STDERR_FILENO};
+mp_obj_vfs_posix_file_t mp_sys_stdin_buffer_obj = {{&mp_type_vfs_posix_fileio}, STDIN_FILENO};
+mp_obj_vfs_posix_file_t mp_sys_stdout_buffer_obj = {{&mp_type_vfs_posix_fileio}, STDOUT_FILENO};
+mp_obj_vfs_posix_file_t mp_sys_stderr_buffer_obj = {{&mp_type_vfs_posix_fileio}, STDERR_FILENO};
 
 // Forward declarations.
-const mp_obj_vfs_posix_file_t mp_sys_stdin_obj;
-const mp_obj_vfs_posix_file_t mp_sys_stdout_obj;
-const mp_obj_vfs_posix_file_t mp_sys_stderr_obj;
+mp_obj_vfs_posix_file_t mp_sys_stdin_obj;
+mp_obj_vfs_posix_file_t mp_sys_stdout_obj;
+mp_obj_vfs_posix_file_t mp_sys_stderr_obj;
 
 STATIC void vfs_posix_textio_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     if (dest[0] != MP_OBJ_NULL) {
@@ -332,8 +332,8 @@ MP_DEFINE_CONST_OBJ_TYPE(
     locals_dict, &vfs_posix_rawfile_locals_dict
     );
 
-const mp_obj_vfs_posix_file_t mp_sys_stdin_obj = {{&mp_type_vfs_posix_textio}, STDIN_FILENO};
-const mp_obj_vfs_posix_file_t mp_sys_stdout_obj = {{&mp_type_vfs_posix_textio}, STDOUT_FILENO};
-const mp_obj_vfs_posix_file_t mp_sys_stderr_obj = {{&mp_type_vfs_posix_textio}, STDERR_FILENO};
+mp_obj_vfs_posix_file_t mp_sys_stdin_obj = {{&mp_type_vfs_posix_textio}, STDIN_FILENO};
+mp_obj_vfs_posix_file_t mp_sys_stdout_obj = {{&mp_type_vfs_posix_textio}, STDOUT_FILENO};
+mp_obj_vfs_posix_file_t mp_sys_stderr_obj = {{&mp_type_vfs_posix_textio}, STDERR_FILENO};
 
 #endif // MICROPY_VFS_POSIX