diff --git a/doc/build-helpers/fixed-point-arguments.chapter.md b/doc/build-helpers/fixed-point-arguments.chapter.md
index af6d5912ce37..000dfe097abc 100644
--- a/doc/build-helpers/fixed-point-arguments.chapter.md
+++ b/doc/build-helpers/fixed-point-arguments.chapter.md
@@ -1,46 +1,39 @@
 # Fixed-point arguments of build helpers {#chap-build-helpers-finalAttrs}
 
-As mentioned in the beginning of this part, `stdenv.mkDerivation` could alternatively accept a fixed-point function. The input of this function, typically named `finalAttrs`, is expected to be the final state of the attribute set.  A build helper like this is said to accept **fixed-point arguments**.
+`stdenv.mkDerivation` also accepts a [fixed-point function](#function-library-lib.fixedPoints.fix) instead of a plain attribute set:
 
-Build helpers don't always support fixed-point arguments yet, as support in [`stdenv.mkDerivation`](#mkderivation-recursive-attributes) was first included in Nixpkgs 22.05.
+```nix
+stdenv.mkDerivation (finalAttrs: {
+  pname = "hello";
+  version = "2.12";
 
-## Defining a build helper with `lib.extendMkDerivation` {#sec-build-helper-extendMkDerivation}
+  src = fetchurl {
+    url = "mirror://gnu/hello/hello-${finalAttrs.version}.tar.gz";
+    hash = "sha256-...";
+  };
+})
+```
 
-Developers can use the Nixpkgs library function [`lib.customisation.extendMkDerivation`](#function-library-lib.customisation.extendMkDerivation) to define a build helper supporting fixed-point arguments from an existing one with such support, with an attribute overlay similar to the one taken by [`<pkg>.overrideAttrs`](#sec-pkg-overrideAttrs).
+The function's input, conventionally named `finalAttrs`, is the final state of the attribute set. Here `src` reads `finalAttrs.version` instead of repeating the version string. A build helper like this is said to accept **fixed-point arguments**.
+
+Attributes that reference each other through `finalAttrs` stay correct when changing any of them with [`overrideAttrs`](#sec-pkg-overrideAttrs), because they all access the final values of the fixed-point computation.
+
+`rec` cannot do this: its self-references are fixed when the set is defined and ignore later overrides.
+See [recursive-sets](https://nix.dev/manual/nix/stable/language/syntax#recursive-sets) for the underlying mechanism.
+
+## Define a build helper with `lib.extendMkDerivation` {#sec-build-helper-extendMkDerivation}
+
+Use [`lib.customisation.extendMkDerivation`](#function-library-lib.customisation.extendMkDerivation) to define a build helper with fixed-point support from an existing one. It takes an attribute overlay similar to [`<pkg>.overrideAttrs`](#sec-pkg-overrideAttrs).
 
 Besides overriding, `lib.extendMkDerivation` also supports `excludeDrvArgNames` to optionally exclude some arguments in the input fixed-point arguments from passing down to the base build helper (specified as `constructDrv`).
 
 :::{.example #ex-build-helpers-extendMkDerivation}
 
-# Example definition of `mkLocalDerivation` extended from `stdenv.mkDerivation` with `lib.extendMkDerivation`
+# Example `mkLocalDerivation` - a build helper over `mkDerivation`
 
-We want to define a build helper named `mkLocalDerivation` that builds locally without using substitutes by default.
+Define a build helper named `mkLocalDerivation` that builds locally without using substitutes by default.
 
-Instead of taking a plain attribute set,
-
-```nix
-{
-  preferLocalBuild ? true,
-  allowSubstitute ? false,
-  specialArg ? (_: false),
-  ...
-}@args:
-
-stdenv.mkDerivation (
-  removeAttrs [
-    # Don't pass specialArg into mkDerivation.
-    "specialArg"
-  ] args
-  // {
-    # Arguments to pass
-    inherit preferLocalBuild allowSubstitute;
-    # Some expressions involving specialArg
-    greeting = if specialArg "hi" then "hi" else "hello";
-  }
-)
-```
-
-we could define with `lib.extendMkDerivation` an attribute overlay to make the result build helper also accept the attribute set's fixed point passing to the underlying `stdenv.mkDerivation`, named `finalAttrs` here:
+Use `lib.extendMkDerivation`:
 
 ```nix
 lib.extendMkDerivation {
@@ -67,4 +60,8 @@ lib.extendMkDerivation {
 ```
 :::
 
-If one needs to apply extra changes to the result derivation, pass the derivation transformation function to `lib.extendMkDerivation` as `lib.customisation.extendMkDerivation { transformDrv = drv: ...; }`.
+To apply extra changes to the result derivation, pass `transformDrv` to `lib.extendMkDerivation`:
+
+```nix
+lib.customisation.extendMkDerivation { transformDrv = drv: /...; }
+```