diff --git a/pkgs/by-name/zx/zxing-cpp/package.nix b/pkgs/by-name/zx/zxing-cpp/package.nix
index affac873f2cd..e162d3c40673 100644
--- a/pkgs/by-name/zx/zxing-cpp/package.nix
+++ b/pkgs/by-name/zx/zxing-cpp/package.nix
@@ -18,6 +18,12 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-teFspdATn9M7Z1vSr/7PdJx/xAv+TVai8rIekxqpBZk=";
   };
 
+  # c++ 20 needed for char8_t or clang-19 build fails
+  postPatch = ''
+    substituteInPlace CMakeLists.txt \
+      --replace-fail "CMAKE_CXX_STANDARD 17" "CMAKE_CXX_STANDARD 20"
+  '';
+
   nativeBuildInputs = [
     cmake
     pkg-config