diff --git a/flake.nix b/flake.nix
index 736910b..ed921bc 100644
--- a/flake.nix
+++ b/flake.nix
@@ -95,6 +95,8 @@
           cargo-release
           rustStable
         ];
+
+        CARGO_REGISTRIES_CRATES_IO_PROTOCOL = "sparse";
       };
     });
 }