diff --git a/doc/stdenv/meta.chapter.md b/doc/stdenv/meta.chapter.md
index e4970f7e9649..ac518cee524c 100644
--- a/doc/stdenv/meta.chapter.md
+++ b/doc/stdenv/meta.chapter.md
@@ -114,6 +114,10 @@ For details, see [Licenses](#sec-meta-license).
 
 A list of the maintainers of this Nix expression. Maintainers are defined in [`nixpkgs/maintainers/maintainer-list.nix`](https://github.com/NixOS/nixpkgs/blob/master/maintainers/maintainer-list.nix). There is no restriction to becoming a maintainer, just add yourself to that list in a separate commit titled “maintainers: add alice”, and reference maintainers with `maintainers = with lib.maintainers; [ alice bob ]`.
 
+### `mainProgram` {#var-meta-mainProgram}
+
+The name of the main binary for the package. This effects the binary `nix run` executes and falls back to the name of the package. Example: `"rg"`
+
 ### `priority` {#var-meta-priority}
 
 The *priority* of the package, used by `nix-env` to resolve file name conflicts between packages. See the Nix manual page for `nix-env` for details. Example: `"10"` (a low-priority package).