diff --git a/pkgs/development/compilers/llvm/3.7/llvm.nix b/pkgs/development/compilers/llvm/3.7/llvm.nix
index 4ff61b27878..361ae4ba117 100644
--- a/pkgs/development/compilers/llvm/3.7/llvm.nix
+++ b/pkgs/development/compilers/llvm/3.7/llvm.nix
@@ -51,6 +51,8 @@ in stdenv.mkDerivation rec {
     "-DCAN_TARGET_i386=false"
   ];
 
+  NIX_LDFLAGS = "-lpthread"; # no idea what's the problem
+
   postBuild = ''
     rm -fR $out