diff --git a/nixos/modules/services/system/cachix-agent/default.nix b/nixos/modules/services/system/cachix-agent/default.nix
index 5b529c1789e2..aa3b2153422c 100644
--- a/nixos/modules/services/system/cachix-agent/default.nix
+++ b/nixos/modules/services/system/cachix-agent/default.nix
@@ -30,7 +30,7 @@ in {
     };
 
     host = mkOption {
-      type = types.str;
+      type = types.nullOr types.str;
       default = null;
       description = lib.mdDoc "Cachix uri to use.";
     };