diff --git a/ci.nix b/ci.nix
index 89444502..e7cb4b33 100644
--- a/ci.nix
+++ b/ci.nix
@@ -14,10 +14,10 @@ in {
   cache.cachix.arc = {
     enable = true;
     publicKey = "arc.cachix.org-1:DZmhclLkB6UO0rc0rBzNpwFbbaeLfyn+fYccuAy7YVY=";
-    signingKey = null;
   };
   cache.cachix.kittywitch = {
     enable = true;
     publicKey = "kittywitch.cachix.org-1:KIzX/G5cuPw5WgrXad6UnrRZ8UDr7jhXzRTK/lmqyK0=";
+    signingKey = env.get "CACHIX_SIGNING_KEY";
   };
 }