diff --git a/pip-frame.el b/pip-frame.el
index 6ca28bc..75eb6d7 100644
--- a/pip-frame.el
+++ b/pip-frame.el
@@ -4,6 +4,7 @@
 
 ;; Author: Milan Zamazal <pdm@zamazal.org>
 ;; Package-Version: 1
+;; Package-Requires: ((emacs "25.1"))
 ;; Keywords: frames
 ;; URL: https://git.zamazal.org/pdm/pip-frame