diff --git a/pkgs/development/ocaml-modules/estring/default.nix b/pkgs/development/ocaml-modules/estring/default.nix
index c0c8eb51f71..9f04dac343c 100644
--- a/pkgs/development/ocaml-modules/estring/default.nix
+++ b/pkgs/development/ocaml-modules/estring/default.nix
@@ -1,4 +1,8 @@
-{ stdenv, buildOcaml, fetchurl }:
+{ stdenv, buildOcaml, ocaml, fetchurl }:
+
+if stdenv.lib.versionAtLeast ocaml.version "4.06"
+then throw "estring is not available for OCaml ${ocaml.version}"
+else
 
 buildOcaml rec {
   name = "estring";