(unwind-protect
        (progn
          (set-default-file-modes 448)
-         (let ((coding-system-for-write 'binary))
-           (setq process
-                 (apply #'start-process "*GnuPG*" errors-buffer
-                        program args)))
+         (setq process
+               (apply #'binary-start-process "*GnuPG*" errors-buffer
+                      program args))
          (set-process-sentinel process #'ignore)
          (when passphrase
            (process-send-string process (concat passphrase "\n")))