diff --git a/nixos/lib/utils.nix b/nixos/lib/utils.nix
index 49ba2e5c8386..22a2c79843c6 100644
--- a/nixos/lib/utils.nix
+++ b/nixos/lib/utils.nix
@@ -64,8 +64,8 @@ rec {
     let
       s = if builtins.isPath arg then "${arg}"
         else if builtins.isString arg then arg
-        else if builtins.isInt arg || builtins.isFloat arg then toString arg
-        else throw "escapeSystemdExecArg only allows strings, paths and numbers";
+        else if builtins.isInt arg || builtins.isFloat arg || lib.isDerivation arg then toString arg
+        else throw "escapeSystemdExecArg only allows strings, paths, numbers and derivations";
     in
       replaceStrings [ "%" "$" ] [ "%%" "$$" ] (builtins.toJSON s);
 
diff --git a/pkgs/tools/networking/kea/default.nix b/pkgs/tools/networking/kea/default.nix
index 574afb68e237..5bdb7bd7607b 100644
--- a/pkgs/tools/networking/kea/default.nix
+++ b/pkgs/tools/networking/kea/default.nix
@@ -87,7 +87,6 @@ stdenv.mkDerivation rec {
   passthru.tests = {
     kea = nixosTests.kea;
     prefix-delegation = nixosTests.systemd-networkd-ipv6-prefix-delegation;
-    prometheus-exporter = nixosTests.prometheus-exporters.kea;
     networking-scripted = lib.recurseIntoAttrs { inherit (nixosTests.networking.scripted) dhcpDefault dhcpSimple dhcpOneIf; };
     networking-networkd = lib.recurseIntoAttrs { inherit (nixosTests.networking.networkd) dhcpDefault dhcpSimple dhcpOneIf; };
   };