diff --git a/common/nix.nix b/common/nix.nix
index 9bb1c91..6c8c25e 100644
--- a/common/nix.nix
+++ b/common/nix.nix
@@ -11,4 +11,11 @@
     setNixPath = true;
     setFlakeRegistry = true;
   };
+
+  # Use our cache and trust its signing key. Still use cache.nixos.org as
+  # fallback.
+  nix.settings.substituters = [ "https://bagel-cache.s3-web.delroth.net/" ];
+  nix.settings.trusted-public-keys = [
+    "cache.forkos.org:xfXIUJO1yiEITJmYsVmNDa9BFSlgTh/YqZ+4ei1EhQg="
+  ];
 }