diff --git a/pkgs/by-name/li/libuchardet/package.nix b/pkgs/by-name/li/libuchardet/package.nix
index 321a1d042576..b2645715dced 100644
--- a/pkgs/by-name/li/libuchardet/package.nix
+++ b/pkgs/by-name/li/libuchardet/package.nix
@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchurl,
+  fetchpatch,
   cmake,
 }:
 
@@ -21,6 +22,15 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-6Xpgz8AKHBR6Z0sJe7FCKr2fp4otnOPz/cwueKNKxfA=";
   };
 
+  patches = [
+    # Fix the build with CMake 4.
+    (fetchpatch {
+      name = "uchardet-cmake-4.patch";
+      url = "https://gitlab.freedesktop.org/uchardet/uchardet/-/commit/6e163c978a7c13a6d3ff64a1e3dd4ba81d2d9e09.patch";
+      hash = "sha256-WXIQEoIpT7b5vELAfQJFEt2hiYrlnGCjV7ILCmd9kqY=";
+    })
+  ];
+
   nativeBuildInputs = [ cmake ];
 
   doCheck = !stdenv.hostPlatform.isi686; # tests fail on i686