diff --git a/pkgs/development/tools/ocaml/cppo/default.nix b/pkgs/development/tools/ocaml/cppo/default.nix
index d6327010e30..63c169f045f 100644
--- a/pkgs/development/tools/ocaml/cppo/default.nix
+++ b/pkgs/development/tools/ocaml/cppo/default.nix
@@ -6,9 +6,14 @@ in
 assert stdenv.lib.versionAtLeast ocaml.version "3.12";
 
 let param =
-  if stdenv.lib.versionAtLeast ocaml.version "4.02" then {
+  if stdenv.lib.versionAtLeast ocaml.version "4.02" then
+   (if stdenv.lib.versionAtLeast ocaml.version "4.03" then {
+    version = "1.6.6";
+    sha256 = "1smcc0l6fh2n0y6bp96c69j5nw755jja99w0b206wx3yb2m4w2hs";
+   } else {
     version = "1.6.5";
     sha256 = "03c0amszy28shinvz61hm340jz446zz5763a1pdqlza36kwcj0p0";
+   }) // {
     buildInputs = [ dune ];
     extra = {
       inherit (dune) installPhase;