diff --git a/modules/system/meta/domains.nix b/modules/system/meta/domains.nix
index 282e25f..5771d80 100644
--- a/modules/system/meta/domains.nix
+++ b/modules/system/meta/domains.nix
@@ -42,14 +42,15 @@ in
             })
           )
           |> lib.groupBy (entry: builtins.toString entry.domain)
-          |> lib.filterAttrs (_: entries: lib.length entries > 1);
+          |> lib.mapAttrs (_: values: values |> lib.map (value: value.file))
+          |> lib.filterAttrs (_: files: lib.length files > 1);
 
         errorMessage =
           duplicateDomains
           |> lib.mapAttrsToList (
-            domain: entries:
-            "Duplicate domain \"${domain}\" found in:\n"
-            + (entries |> lib.map (entry: "  - ${entry.file}") |> lib.concatLines)
+            domain: files:
+            "Duplicate domain `${domain}` found in:\n"
+            + (files |> lib.map (file: "  - ${file}") |> lib.concatLines)
           )
           |> lib.concatStrings;
       in
diff --git a/modules/system/meta/ports.nix b/modules/system/meta/ports.nix
index 86d05c8..95a18b9 100644
--- a/modules/system/meta/ports.nix
+++ b/modules/system/meta/ports.nix
@@ -36,15 +36,15 @@ in
             })
           )
           |> lib.groupBy (entry: builtins.toString entry.port)
-          |> lib.filterAttrs (_: entries: lib.length entries > 1);
+          |> lib.mapAttrs (_: values: values |> lib.map (value: value.file))
+          |> lib.filterAttrs (_: files: lib.length files > 1);
 
         mkErrorMessage =
           duplicatePorts:
           duplicatePorts
           |> lib.mapAttrsToList (
-            port: entries:
-            "Duplicate port ${port} found in:\n"
-            + (entries |> lib.map (entry: "  - ${entry.file}") |> lib.concatLines)
+            port: files:
+            "Duplicate port `${port}` found in:\n" + (files |> lib.map (file: "  - ${file}") |> lib.concatLines)
           )
           |> lib.concatStrings;