diff --git a/pkgs/development/compilers/ocaml/generic.nix b/pkgs/development/compilers/ocaml/generic.nix
index 1ed6d2c6db2..d1ee43c9152 100644
--- a/pkgs/development/compilers/ocaml/generic.nix
+++ b/pkgs/development/compilers/ocaml/generic.nix
@@ -24,11 +24,13 @@ let
    name = "ocaml${optionalString flambdaSupport "+flambda"}-${version}";
 in
 
-stdenv.mkDerivation (args // rec {
-
+let
   x11env = buildEnv { name = "x11env"; paths = [libX11 xproto]; };
   x11lib = x11env + "/lib";
   x11inc = x11env + "/include";
+in
+
+stdenv.mkDerivation (args // rec {
 
   inherit name;
   inherit version;