diff --git a/nixos/modules/services/scheduling/fcron.nix b/nixos/modules/services/scheduling/fcron.nix
index 8b87f72811a3..ac589be57736 100644
--- a/nixos/modules/services/scheduling/fcron.nix
+++ b/nixos/modules/services/scheduling/fcron.nix
@@ -146,7 +146,7 @@ in
           --group fcron \
           --directory /var/spool/fcron
         # load system crontab file
-        /run/wrappers/bin/fcrontab -u systab ${pkgs.writeText "systab" cfg.systab}
+        /run/wrappers/bin/fcrontab -u systab - < ${pkgs.writeText "systab" cfg.systab}
       '';
 
       serviceConfig = {