diff --git a/nixos/modules/services/monitoring/prometheus/exporters.nix b/nixos/modules/services/monitoring/prometheus/exporters.nix
index 46015c9ec1ef..6bd075697fa2 100644
--- a/nixos/modules/services/monitoring/prometheus/exporters.nix
+++ b/nixos/modules/services/monitoring/prometheus/exporters.nix
@@ -180,7 +180,7 @@ let
         serviceConfig.PrivateTmp = mkDefault true;
         serviceConfig.WorkingDirectory = mkDefault /tmp;
         serviceConfig.DynamicUser = mkDefault enableDynamicUser;
-        serviceConfig.User = conf.user;
+        serviceConfig.User = mkDefault conf.user;
         serviceConfig.Group = conf.group;
       } serviceOpts ]);
   };