diff --git a/modules/binary-cache.nix b/modules/binary-cache.nix
index a53ebf4..4dcf034 100644
--- a/modules/binary-cache.nix
+++ b/modules/binary-cache.nix
@@ -5,7 +5,7 @@ let
 in
 {
   options = {
-    c3d2.addBinaryCache = lib.mkOption "add hydra.hq.c3d2.de as a trusted substituter";
+    c3d2.addBinaryCache = lib.mkEnableOption (lib.mdDoc "add hydra.hq.c3d2.de as a trusted substituter");
   };
 
   config = lib.mkIf cfg {