diff --git a/pkgs/misc/emulators/dlx/default.nix b/pkgs/misc/emulators/dlx/default.nix
index 9cb761264ec..c23b60c29b3 100644
--- a/pkgs/misc/emulators/dlx/default.nix
+++ b/pkgs/misc/emulators/dlx/default.nix
@@ -10,6 +10,8 @@ stdenv.mkDerivation {
 
   buildInputs = [ unzip ];
 
+  makeFlags = "LINK=gcc CFLAGS=-O2";
+
   installPhase = ''
     mkdir -p $out/include/dlx $out/share/dlx/{examples,doc} $out/bin
     mv -v masm mon dasm $out/bin/