diff --git a/packages.el b/packages.el
index 50da9cc..bc9895f 100644
--- a/packages.el
+++ b/packages.el
@@ -41,6 +41,10 @@
   :ensure t
   :config
   (setq inferior-lisp-program "sbcl")
+  (add-hook 'sly-mode-hook
+            (lambda ()
+              (defun sly-flash-region (start end)
+                (fez/flash-region))))
   (use-package sly-quicklisp
     :ensure t))