diff --git a/pkgs/development/ruby-modules/gem-config/default.nix b/pkgs/development/ruby-modules/gem-config/default.nix
index 3c355d08576..c79a586e5f3 100644
--- a/pkgs/development/ruby-modules/gem-config/default.nix
+++ b/pkgs/development/ruby-modules/gem-config/default.nix
@@ -395,4 +395,8 @@ in
     '';
   };
 
+   zookeeper = attrs: {
+     buildInputs = stdenv.lib.optionals stdenv.isDarwin [ darwin.cctools ];
+   };
+
 }