From bf60e5144c8dd9f0cd92a92442e942de564dc334 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@gmail.com>
Date: Mon, 18 Oct 2021 16:13:14 +0200
Subject: [PATCH] unbound: use lib.optionalString

---
 pkgs/tools/networking/unbound/default.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkgs/tools/networking/unbound/default.nix b/pkgs/tools/networking/unbound/default.nix
index 393756a9b2ab..bd994c2640f9 100644
--- a/pkgs/tools/networking/unbound/default.nix
+++ b/pkgs/tools/networking/unbound/default.nix
@@ -82,7 +82,7 @@ stdenv.mkDerivation rec {
     "--with-libhiredis=${hiredis}"
   ];
 
-  PROTOC_C = if withDNSTAP then "${protobufc}/bin/protoc-c" else null;
+  PROTOC_C = lib.optionalString withDNSTAP "${protobufc}/bin/protoc-c";
 
   # Remove references to compile-time dependencies that are included in the configure flags
   postConfigure = let