diff --git a/pkgs/build-support/ocaml/dune.nix b/pkgs/build-support/ocaml/dune.nix
index 81f1010e467c..7b602e2507d5 100644
--- a/pkgs/build-support/ocaml/dune.nix
+++ b/pkgs/build-support/ocaml/dune.nix
@@ -32,7 +32,7 @@ stdenv.mkDerivation ({
     runHook preInstall
     dune install --prefix $out --libdir $OCAMLFIND_DESTDIR ${pname} \
      ${if lib.versionAtLeast Dune.version "2.9"
-       then "--docdir $out/share/doc --man $out/share/man"
+       then "--docdir $out/share/doc --mandir $out/share/man"
        else ""}
     runHook postInstall
   '';