How can I fix shift-select-mode with own syntax-table

So I have modified syntax table for moving with C-<left>.

 (defvar my-wacky-syntax-table
      (let ((table (make-syntax-table)))
        (modify-syntax-entry ?\( "w" table)
        (modify-syntax-entry ?\) "w" table)
        table))

(defun Pfedj/my-backward-word()
  (interactive)
  (with-syntax-table my-wacky-syntax-table
          (backward-char)))

(global-set-key (kbd "C-<left>") 'Pfedj/my-backward-word)

It works fine for moving, but S-C-<left> for selecting with control does not work now. How can I fixed it?