From b661ebe3cbef28e81ea70f42cc6ea6af16a30144 Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Thu, 20 Aug 2015 08:09:55 -0400
Subject: [PATCH] rcs: Use c99 on darwin

---
 pkgs/applications/version-management/rcs/default.nix | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pkgs/applications/version-management/rcs/default.nix b/pkgs/applications/version-management/rcs/default.nix
index 266ab81777bd..a829af8aa235 100644
--- a/pkgs/applications/version-management/rcs/default.nix
+++ b/pkgs/applications/version-management/rcs/default.nix
@@ -12,6 +12,8 @@ stdenv.mkDerivation rec {
 
   doCheck = true;
 
+  NIX_CFLAGS_COMPILE = if stdenv.isDarwin then "-std=gnu99" else null;
+
   meta = {
     homepage = http://www.gnu.org/software/rcs/;
     description = "Revision control system";