diff --git a/pkgs/games/openra/build-engine.nix b/pkgs/games/openra/build-engine.nix
index 31d0f84fce99..85644fadef06 100644
--- a/pkgs/games/openra/build-engine.nix
+++ b/pkgs/games/openra/build-engine.nix
@@ -35,6 +35,9 @@ buildDotnetModule rec {
 
   dontDotnetFixup = true;
 
+  # Microsoft.NET.Publish.targets(248,5): error MSB3021: Unable to copy file "[...]/Newtonsoft.Json.dll" to "[...]/Newtonsoft.Json.dll". Access to the path '[...]Newtonsoft.Json.dll' is denied. [/build/source/OpenRA.Mods.Cnc/OpenRA.Mods.Cnc.csproj]
+  enableParallelBuilding = false;
+
   preBuild = ''
     make VERSION=${engine.build}-${version} version
   '';