diff --git a/pkgs/development/tools/ocaml/dune/1.nix b/pkgs/development/tools/ocaml/dune/1.nix
index a16b3ab23f2..ad908787911 100644
--- a/pkgs/development/tools/ocaml/dune/1.nix
+++ b/pkgs/development/tools/ocaml/dune/1.nix
@@ -2,7 +2,7 @@
 
 if !lib.versionAtLeast ocaml.version "4.02"
 || lib.versionAtLeast ocaml.version "4.12"
-then throw "dune is not available for OCaml ${ocaml.version}"
+then throw "dune 1 is not available for OCaml ${ocaml.version}"
 else
 
 stdenv.mkDerivation rec {
diff --git a/pkgs/development/tools/ocaml/dune/2.nix b/pkgs/development/tools/ocaml/dune/2.nix
index f1365792fbc..2acc7e5bdf3 100644
--- a/pkgs/development/tools/ocaml/dune/2.nix
+++ b/pkgs/development/tools/ocaml/dune/2.nix
@@ -1,7 +1,7 @@
 { lib, stdenv, fetchurl, ocaml, findlib }:
 
 if lib.versionOlder ocaml.version "4.08"
-then throw "dune is not available for OCaml ${ocaml.version}"
+then throw "dune 2 is not available for OCaml ${ocaml.version}"
 else
 
 stdenv.mkDerivation rec {