From 47f198979b81813ae17ebc58b4714642e465ce04 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Mon, 5 Jan 2026 22:03:09 -0400
Subject: [PATCH] gnum4: fix cygwin build

---
 pkgs/by-name/gn/gnum4/package.nix | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pkgs/by-name/gn/gnum4/package.nix b/pkgs/by-name/gn/gnum4/package.nix
index 7f11614842a2..9f0172f26017 100644
--- a/pkgs/by-name/gn/gnum4/package.nix
+++ b/pkgs/by-name/gn/gnum4/package.nix
@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchurl,
+  gnulib,
 }:
 
 # Note: this package is used for bootstrapping fetchurl, and thus
@@ -18,6 +19,8 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-rGmJ7l0q7YFzl4BjDMLOCX4qZUb+uWpKVNs31GoUUuQ=";
   };
 
+  patches = lib.optional stdenv.hostPlatform.isCygwin gnulib.patches.memcpy-fix-backport-250512;
+
   # this could be accomplished by updateAutotoolsGnuConfigScriptsHook, but that causes infinite recursion
   # necessary for FreeBSD code path in configure
   postPatch = ''