1 files changed, 2 insertions, 2 deletions

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 10845b23630..5073f2bc23a 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -1127,8 +1127,8 @@ Don't save anything for STR matching `inferior-python-filter-regexp'."
         ((string-match ".*\n" s)
          s)
         ((or (eq t (compare-strings s nil nil "_emacs_ok\n" nil (length s)))
-             (eq t (compare-strings s nil nil "_emacs_out " nil
-                                    (min (length "_emacs_out ") (length s)))))
+             (let ((end (min (length "_emacs_out ") (length s))))
+               (eq t (compare-strings s nil end "_emacs_out " nil end))))
          (setq python-preoutput-leftover s)
          "")
         (t s)))