diff --git a/pkgs/tools/text/gnupatch/default.nix b/pkgs/tools/text/gnupatch/default.nix
index 272eaee785c..26e0b906e52 100644
--- a/pkgs/tools/text/gnupatch/default.nix
+++ b/pkgs/tools/text/gnupatch/default.nix
@@ -1,6 +1,6 @@
 {stdenv, fetchurl}:
 
-stdenv.mkDerivation {
+stdenv.mkDerivation ( {
   name = "gnupatch-2.5.4";
   src = fetchurl {
     url = mirror://gnu/patch/patch-2.5.4.tar.gz;
@@ -10,6 +10,6 @@ stdenv.mkDerivation {
   # Hack around ancient configure script: doesn't build on many newer
   # platforms unless a platform is specified.
   configureFlags = "dummy";
-  
+
   patches = if stdenv.isDarwin then [./setmode.patch] else [];
-}
+} // (if stdenv.isDarwin then { ac_cv_exeext = "" ; } else {} ) )