diff --git a/pkgs/by-name/do/docbook2x/package.nix b/pkgs/by-name/do/docbook2x/package.nix
index fbbe6e3daeb2..3413918f9499 100644
--- a/pkgs/by-name/do/docbook2x/package.nix
+++ b/pkgs/by-name/do/docbook2x/package.nix
@@ -54,7 +54,7 @@ stdenv.mkDerivation (finalAttrs: {
   # configure tries to find osx in PATH and hardcodes the resulting path
   # (if any) on the Perl code. this fails under strictDeps, so override
   # the autoconf test:
-  OSX = "${opensp}/bin/osx";
+  env.OSX = "${opensp}/bin/osx";
 
   postConfigure = ''
     # Broken substitution is used for `perl/config.pl', which leaves literal