diff --git a/default.nix b/default.nix
index 1a1f679..39d3355 100644
--- a/default.nix
+++ b/default.nix
@@ -40,6 +40,12 @@ in
       ];
       # trusted-users = [ "administration" ];
       auto-optimise-store = true;
+      trusted-substituters = [
+        "https://gradient.adm.htw.stura-dresden.de/cache/stura"
+      ];
+      trusted-public-keys = [
+        "gradient.adm.htw.stura-dresden.de-stura:rVy7JDos8CTvKJsrotP2/y/ICbCNv69HKy0Dfsgrafs="
+      ];
     };
     optimise.automatic = true;
     gc = {