diff --git a/pkgs/development/ocaml-modules/ulex/default.nix b/pkgs/development/ocaml-modules/ulex/default.nix
index 28950078f39e..7c8acafe769e 100644
--- a/pkgs/development/ocaml-modules/ulex/default.nix
+++ b/pkgs/development/ocaml-modules/ulex/default.nix
@@ -1,4 +1,4 @@
-{stdenv, fetchurl, ocaml, findlib }:
+{ stdenv, fetchurl, ocaml, findlib, camlp4 }:
 
 let
   ocaml_version = (builtins.parseDrvName ocaml.name).version;
@@ -17,7 +17,8 @@ stdenv.mkDerivation {
 
   createFindlibDestdir = true;
 
-  buildInputs = [ocaml findlib];
+  buildInputs = [ ocaml findlib ];
+  propagatedBuildInputs = [ camlp4 ];
 
   buildFlags = "all all.opt";