diff --git a/pkgs/games/commandergenius/default.nix b/pkgs/games/commandergenius/default.nix
index 568dcc7e51e1..d3549fd211f2 100644
--- a/pkgs/games/commandergenius/default.nix
+++ b/pkgs/games/commandergenius/default.nix
@@ -28,10 +28,14 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ SDL2 SDL2_image SDL2_mixer SDL2_ttf libGL boost libvorbis zlib curl python3 ];
 
-  preConfigure = ''
-    export cmakeFlags="$cmakeFlags -DCMAKE_INSTALL_PREFIX=$out -DSHAREDIR=$out/share"
-    export makeFlags="$makeFlags DESTDIR=$(out)"
-  '';
+  cmakeFlags = [
+    "-DCMAKE_INSTALL_PREFIX=${placeholder "out"}"
+    "-DSHAREDIR=${placeholder "out"}/share"
+  ];
+
+  makeFlags = [
+    "DESTDIR=${placeholder "out"}"
+  ];
 
   nativeBuildInputs = [ cmake pkg-config ];