diff --git a/flake.nix b/flake.nix
index 1abf156..3cbd238 100644
--- a/flake.nix
+++ b/flake.nix
@@ -55,15 +55,6 @@
       };
       cranePkgs = makeCranePkgs pkgs;
 
-      internalMatrix = lib.mapAttrs (_: nix: let
-        cranePkgs' = cranePkgs.override { inherit nix; };
-      in {
-        inherit (cranePkgs') attic-tests cargoArtifacts;
-      }) {
-        "2.20" = pkgs.nixVersions.nix_2_20;
-        "2.24" = pkgs.nixVersions.nix_2_24;
-        "default" = pkgs.nix;
-      };
 
       pkgsStable = import inputs.nixpkgs-stable {
         inherit system;
@@ -73,8 +64,6 @@
 
       inherit (pkgs) lib;
     in rec {
-      inherit internalMatrix;
-
       checks = let
         makeIntegrationTests = pkgs: import ./integration-tests {
           pkgs = import inputs.nixpkgs {
diff --git a/flake/nix-versions.nix b/flake/nix-versions.nix
index 66f3697..b0b8df6 100644
--- a/flake/nix-versions.nix
+++ b/flake/nix-versions.nix
@@ -1,4 +1,4 @@
-{ lib, flake-parts-lib, ... }:
+{ lib, flake-parts-lib, config, ... }:
 let
   inherit (lib)
     mkOption
@@ -20,11 +20,17 @@ in
           type = types.package;
         };
       };
+
+      options.internalMatrix = mkOption {
+        type = types.attrsOf (types.attrsOf types.package);
+      };
     };
   };
 
   config = {
-    perSystem = { self', pkgs, config, ... }: let
+    flake.internalMatrix = lib.mapAttrs (system: ps: ps.internalMatrix) config.allSystems;
+
+    perSystem = { self', pkgs, config, cranePkgs, ... }: let
       cfg = config.attic.nix-versions;
     in {
       attic.nix-versions = {
@@ -47,6 +53,12 @@ in
           }) cfg.versions;
         in pkgs.writeText "nix-versions.json" (builtins.toJSON manifest);
       };
+
+      internalMatrix = lib.mapAttrs (_: nix: let
+        cranePkgs' = cranePkgs.override { inherit nix; };
+      in {
+        inherit (cranePkgs') attic-tests cargoArtifacts;
+      }) cfg.versions;
     };
   };
 }