diff --git a/des-compat.h b/des-compat.h
index 1ec9a202c7939ce30af1133d0bf5c1e7a0033d85..baff1774ffab93f734630004de750f3935eca580 100644
--- a/des-compat.h
+++ b/des-compat.h
@@ -50,6 +50,7 @@
 #define des_is_weak_key nettle_openssl_des_is_weak_key
 
 /* An extra alias */
+#undef des_set_key
 #define des_set_key nettle_openssl_des_key_sched
 
 enum { DES_DECRYPT = 0, DES_ENCRYPT = 1 };