diff --git a/default.nix b/default.nix
index 9fddf0d..17a5257 100644
--- a/default.nix
+++ b/default.nix
@@ -1,13 +1,16 @@
 { ... }:
 let
     pkgs = import <nixpkgs> {};
-    inherit (pkgs) stdenv autoPatchelfHook;
+    inherit (pkgs) stdenv fetchurl autoPatchelfHook;
 in {
     MultiMC = stdenv.mkDerivation rec {
         pname = "MultiMC";
         version = "develop";
-    
-        src = builtins.fetchTarball "https://files.multimc.org/downloads/mmc-develop-lin64.tar.gz";
+        
+        src = fetchurl {
+            url = "https://files.multimc.org/downloads/mmc-develop-lin64.tar.gz";
+            sha256 = "c70c9b8d152d33d2f64d91109939a2f21f9717cf0d16e316c796443273141e15";
+        };
 
         nativeBuildInputs = with pkgs; [ autoPatchelfHook qt5.wrapQtAppsHook ];