diff --git a/pkgs/by-name/ji/jing-trang/package.nix b/pkgs/by-name/ji/jing-trang/package.nix
index d7c72c56232d..8e03b7f8d8e1 100644
--- a/pkgs/by-name/ji/jing-trang/package.nix
+++ b/pkgs/by-name/ji/jing-trang/package.nix
@@ -28,7 +28,7 @@ stdenv.mkDerivation (finalAttrs: {
     saxon
   ];
 
-  CLASSPATH = "lib/saxon.jar";
+  env.CLASSPATH = "lib/saxon.jar";
 
   patches = [
     ./no-git-during-build.patch