diff --git a/nixos/doc/manual/release-notes/rl-1909.xml b/nixos/doc/manual/release-notes/rl-1909.xml
index 951040a0648f..c0de8b4d2fd3 100644
--- a/nixos/doc/manual/release-notes/rl-1909.xml
+++ b/nixos/doc/manual/release-notes/rl-1909.xml
@@ -211,6 +211,24 @@
       RuntimeDirectory and tmpfiles.
     </para>
    </listitem>
+  <listitem>
+    <para>
+      Since version 0.1.19, <literal>cargo-vendor</literal> honors package
+      includes that are specified in the <filename>Cargo.toml</filename>
+      file of Rust crates. <literal>rustPlatform.buildRustPackage</literal> uses
+      <literal>cargo-vendor</literal> to collect and build dependent crates.
+      Since this change in <literal>cargo-vendor</literal> changes the set of
+      vendored files for most Rust packages, the hash that use used to verify
+      the dependencies, <literal>cargoSha256</literal>, also changes.
+    </para>
+
+    <para>
+      The <literal>cargoSha256</literal> hashes of all in-tree derivations that
+      use <literal>buildRustPackage</literal> have been updated to reflect this
+      change. However, third-party derivations that use
+      <literal>buildRustPackage</literal> may have to be updated as well.
+    </para>
+   </listitem>
   </itemizedlist>
  </section>
 </section>