diff --git a/nixos/modules/system/boot/systemd.nix b/nixos/modules/system/boot/systemd.nix
index d44c2e234b0..d1f3f923e5e 100644
--- a/nixos/modules/system/boot/systemd.nix
+++ b/nixos/modules/system/boot/systemd.nix
@@ -777,7 +777,7 @@ in
         { wantedBy = [ "timers.target" ];
           timerConfig.OnCalendar = service.startAt;
         })
-        (filterAttrs (name: service: service.enable && service.startAt != "") cfg.services);
+        (filterAttrs (name: service: service.enable && service.startAt != []) cfg.services);
 
     # Generate timer units for all services that have a ‘startAt’ value.
     systemd.user.timers =
@@ -785,7 +785,7 @@ in
         { wantedBy = [ "timers.target" ];
           timerConfig.OnCalendar = service.startAt;
         })
-        (filterAttrs (name: service: service.startAt != "") cfg.user.services);
+        (filterAttrs (name: service: service.startAt != []) cfg.user.services);
 
     systemd.sockets.systemd-journal-gatewayd.wantedBy =
       optional config.services.journald.enableHttpGateway "sockets.target";