diff --git a/nix/shell.nix b/nix/shell.nix
index a0647a4..4559ca1 100644
--- a/nix/shell.nix
+++ b/nix/shell.nix
@@ -17,7 +17,7 @@ mkShell {
     cargo
 
     # Tools
-    rustfmt
+    (rustfmt.override {asNightly = true;})
     clippy
     cargo
     taplo
@@ -26,5 +26,5 @@ mkShell {
     rust-analyzer-unwrapped
   ];
 
-  RUST_SRC_PATH = "${rustPlatform.rustLibSrc}";
-}
\ No newline at end of file
+  env.RUST_SRC_PATH = "${rustPlatform.rustLibSrc}";
+}