diff --git a/pkgs/by-name/mu/mudlet/package.nix b/pkgs/by-name/mu/mudlet/package.nix
index e7b7e0e26883..981ca5159bf8 100644
--- a/pkgs/by-name/mu/mudlet/package.nix
+++ b/pkgs/by-name/mu/mudlet/package.nix
@@ -103,8 +103,10 @@ stdenv.mkDerivation (finalAttrs: {
     "-DCMAKE_SKIP_BUILD_RPATH=ON"
   ];
 
-  WITH_FONTS = "NO";
-  WITH_UPDATER = "NO";
+  env = {
+    WITH_FONTS = "NO";
+    WITH_UPDATER = "NO";
+  };
 
   installPhase = ''
     runHook preInstall