diff --git a/pkgs/development/compilers/llvm/3.9/libc++abi.nix b/pkgs/development/compilers/llvm/3.9/libc++abi.nix
index 1ad2cb102950..65345ca69925 100644
--- a/pkgs/development/compilers/llvm/3.9/libc++abi.nix
+++ b/pkgs/development/compilers/llvm/3.9/libc++abi.nix
@@ -5,7 +5,9 @@ stdenv.mkDerivation {
 
   src = fetch "libcxxabi" "1qi9q06zanqm8awzq83810avmvi52air6gr9zfip8mbg5viqn3cj";
 
-  buildInputs = [ cmake ] ++ stdenv.lib.optional (!stdenv.isDarwin && !stdenv.isFreeBSD) libunwind;
+  nativeBuildInputs = [ cmake ];
+
+  buildInputs = stdenv.lib.optional (!stdenv.isDarwin && !stdenv.isFreeBSD) libunwind;
 
   postUnpack = ''
     unpackFile ${libcxx.src}