diff --git a/pkgs/development/libraries/brunsli/default.nix b/pkgs/development/libraries/brunsli/default.nix
index 119814eeecfd..03c9b02f7f9f 100644
--- a/pkgs/development/libraries/brunsli/default.nix
+++ b/pkgs/development/libraries/brunsli/default.nix
@@ -35,6 +35,8 @@ stdenv.mkDerivation rec {
 
   postPatch = ''
     rm -r third_party
+  '' + lib.optionalString stdenv.isDarwin ''
+    rm -r build
   '';
 
   nativeBuildInputs = [