diff --git a/buer.scm b/buer.scm
index 79c656c..cf4d860 100644
--- a/buer.scm
+++ b/buer.scm
@@ -174,7 +174,7 @@
         #|Mcron service|#
         (simple-service 'mcron-jobs mcron-service-type
                         (list #~(job "5 0 * * *"
-                                     "guix gc --optimize -F 5G")))
+                                     "guix gc --optimize --free-space=5G")))
 
         #|Device management services|#
         (service udev-service-type