diff --git a/pkgs/development/ocaml-modules/bitstring/default.nix b/pkgs/development/ocaml-modules/bitstring/default.nix
index b612ec1c0bdb..d48f93bd626e 100644
--- a/pkgs/development/ocaml-modules/bitstring/default.nix
+++ b/pkgs/development/ocaml-modules/bitstring/default.nix
@@ -17,7 +17,7 @@ buildOcaml rec {
   createFindlibDestdir = true;
   hasSharedObjects = true;
 
-  preConfigure = "./bootstrap; echo breakhash";
+  preConfigure = "./bootstrap";
 
   meta = with stdenv.lib; {
     description = "This library adds Erlang-style bitstrings and matching over bitstrings as a syntax extension and library for OCaml.";