diff --git a/nixos-modules/genode-core.nix b/nixos-modules/genode-core.nix
index 0a243d2..9e7b298 100644
--- a/nixos-modules/genode-core.nix
+++ b/nixos-modules/genode-core.nix
@@ -70,8 +70,8 @@ let
         (with pkgs.genodePackages; storeBackendInputs ++ coreInputs))
         + lib.optionalString (config.genode.core.romModules != { }) ''
           # [ { mapKey = "romModules", mapValue = [ ${
-            lib.concatStringsSep ", " (lib.lists.flatten ((mapAttrsToList
-              (k: v: ''{ mapKey = "${k}", mapValue = "${v}" }'')
+            lib.concatStringsSep ", " (lib.lists.flatten ((map ({ name, value }:
+              ''{ mapKey = "${name}", mapValue = "${value}" }'')
               config.genode.core.romModules)))
           }] } ]'');
 
@@ -115,9 +115,9 @@ let
     EOF
   '';
 
-  erisContents = lib.attrsets.mapAttrsToList (urn: source: {
-    target = urn;
-    inherit source;
+  erisContents = map ({ name, value }: {
+    target = name;
+    source = value;
   }) config.genode.init.romModules;
 
 in {
@@ -177,8 +177,8 @@ in {
       };
 
       romModules = mkOption {
-        type = types.attrsOf types.path;
-        default = { };
+        type = with lib.types; listOf (attrsOf str);
+        default = [ ];
         description = "Attr set of initial ROM modules";
       };
 
@@ -230,15 +230,20 @@ in {
     }];
 
     genode.core.romModules = with builtins;
-      listToAttrs (lib.lists.flatten
-        ((map (getAttr "roms") (attrValues children')) ++ (map
-          ({ cap, path, ... }: {
-            name = cap;
-            value = path;
-          }) (attrValues coreErisCaps)))) // {
-            "init" = "${pkgs.genodePackages.init}/bin/init";
-            "report_rom" = "${pkgs.genodePackages.report_rom}/bin/report_rom";
-          };
+      (lib.lists.flatten ((map (getAttr "roms") (attrValues children')) ++ (map
+        ({ cap, path, ... }: {
+          name = cap;
+          value = path;
+        }) (attrValues coreErisCaps)))) ++ [
+          {
+            name = "init";
+            value = "${pkgs.genodePackages.init}/bin/init";
+          }
+          {
+            name = "report_rom";
+            value = "${pkgs.genodePackages.report_rom}/bin/report_rom";
+          }
+        ];
 
     genode.core.children.jitter_sponge = {
       package = pkgs.genodePackages.jitter_sponge;
@@ -266,8 +271,8 @@ in {
     system.build.configFile = bootConfigFile;
 
     # Create the tarball of the store to live in core ROM
-    system.build.tarball =
-      pkgs.buildPackages.callPackage "${modulesPath}/../lib/make-system-tarball.nix" {
+    system.build.tarball = pkgs.buildPackages.callPackage
+      "${modulesPath}/../lib/make-system-tarball.nix" {
         extraInputs = lib.attrsets.mapAttrsToList (_: child: child.package)
           config.genode.init.children;
         contents = erisContents;
diff --git a/nixos-modules/genode-init.nix b/nixos-modules/genode-init.nix
index 5799a1e..4d1da45 100644
--- a/nixos-modules/genode-init.nix
+++ b/nixos-modules/genode-init.nix
@@ -77,8 +77,8 @@ in {
     };
 
     romModules = mkOption {
-      type = types.attrsOf types.path;
-      default = { };
+      type = with lib.types; listOf (attrsOf str);
+      default = [ ];
       description = "Attr set of initial ROM modules";
     };
 
@@ -121,8 +121,8 @@ in {
     '';
 
     romModules = with builtins;
-      listToAttrs (lib.lists.flatten
-        (map ({ roms, ... }: roms) (lib.lists.flatten (attrValues children'))));
+      lib.lists.flatten
+      (map ({ roms, ... }: roms) (lib.lists.flatten (attrValues children')));
 
   };
 
diff --git a/nixos-modules/nova.nix b/nixos-modules/nova.nix
index b9d362f..b8ba5ee 100644
--- a/nixos-modules/nova.nix
+++ b/nixos-modules/nova.nix
@@ -26,10 +26,16 @@ in {
   genode.core.image =
     utils.novaImage config.system.name { } config.system.build.configFile;
 
-  genode.core.romModules = {
-    "ld.lib.so" = "${pkgs.genodePackages.base-nova}/lib/ld.lib.so";
-    timer_drv = "${pkgs.genodePackages.base-nova}/bin/timer_drv";
-  };
+  genode.core.romModules = [
+    {
+      name = "ld.lib.so";
+      value = "${pkgs.genodePackages.base-nova}/lib/ld.lib.so";
+    }
+    {
+      name = "timer_drv";
+      value = "${pkgs.genodePackages.base-nova}/bin/timer_drv";
+    }
+  ];
 
   genode.core.storePaths =
     lib.optional (config.genode.core.storeBackend != "memory") bootDir;