diff --git a/hosts/common/programs/smartmontools.nix b/hosts/common/programs/smartmontools.nix
index 9f9a94ba3..efdf6ebb7 100644
--- a/hosts/common/programs/smartmontools.nix
+++ b/hosts/common/programs/smartmontools.nix
@@ -54,7 +54,9 @@ in
       # keep "@privileged" or "@raw-io", since it needs to do that
     ];
     # serviceConfig.RestrictNamespaces = true;
-    serviceConfig.ReadWritePaths = "/var/lib/postfix/queue/maildrop";
+    serviceConfig.ReadWritePaths = lib.mkIf config.services.postfix.enable [
+      "/var/lib/postfix/queue/maildrop"
+    ];
     # serviceConfig.PrivateUsers = true;  # can't, because it requires CAP_SYS_RAWIO
   };
 }