diff --git a/flake.nix b/flake.nix
index af48796e..7dcea35b 100644
--- a/flake.nix
+++ b/flake.nix
@@ -16,6 +16,15 @@
     };
   };
 
+  nixConfig = {
+    extra-substituters = [
+      "https://elmerfem.cachix.org"
+    ];
+    extra-trusted-public-keys = [
+      "elmerfem.cachix.org-1:nWIb5JzEzC2/W6qiuaC0urJRG+S7KvTn9WatX43gkHk="
+    ];
+  };
+
   outputs = inputs@{ self, nixpkgs, flake-utils, ... }:
     with nixpkgs.lib;
     {
diff --git a/modules/elmer.nix b/modules/elmer.nix
index 6774f6f1..e9aae68a 100644
--- a/modules/elmer.nix
+++ b/modules/elmer.nix
@@ -5,6 +5,17 @@ in
 {
   options.wsl.elmer.enable = mkEnableOption "ElmerFEM";
   config = mkIf config.wsl.elmer.enable {
-    environment.systemPackages = [ inputs.elmer.packages.x86_64-linux.gui pkgs.mpi ];
+    nix.settings = {
+      extra-substituters = [
+        "https://elmerfem.cachix.org"
+      ];
+      extra-trusted-public-keys = [
+        "elmerfem.cachix.org-1:nWIb5JzEzC2/W6qiuaC0urJRG+S7KvTn9WatX43gkHk="
+      ];
+    };
+
+    nixpkgs.overlays = [ inputs.elmer.overlay ];
+
+    environment.systemPackages = with pkgs; [ elmer-gui mpi ];
   };
 }