diff --git a/dotnet.nix b/dotnet.nix
new file mode 100644
index 0000000..9e7228c
--- /dev/null
+++ b/dotnet.nix
@@ -0,0 +1,11 @@
+let
+  # Pinned nixpkgs, deterministic. Last updated: 2/12/21.
+  #pkgs = import (fetchTarball("https://github.com/NixOS/nixpkgs/archive/a58a0b5098f0c2a389ee70eb69422a052982d990.tar.gz")) {};
+  # Rolling updates, not deterministic.
+  pkgs = import (fetchTarball "channel:nixpkgs-unstable") { };
+in pkgs.mkShell {
+  buildInputs = [ pkgs.dotnet-sdk ];
+  shellHook = ''
+    exec zsh
+  '';
+}
diff --git a/rust-nightly.nix b/rust-nightly.nix
index 4bc17a9..865c0d4 100644
--- a/rust-nightly.nix
+++ b/rust-nightly.nix
@@ -1,17 +1,15 @@
 let
-  moz_overlay =
-    import (builtins.fetchTarball
-      "https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz");
-  nixpkgs = import <nixpkgs> {overlays = [moz_overlay];};
-in
-  with nixpkgs;
-    stdenv.mkDerivation {
-      name = "moz_overlay_shell";
-      buildInputs = [
-        # to use the latest nightly:
-        nixpkgs.latest.rustChannels.nightly.rust
-      ];
-      shellHook = ''
-        exec zsh
-      '';
-    }
+  moz_overlay = import (builtins.fetchTarball
+    "https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz");
+  nixpkgs = import <nixpkgs> { overlays = [ moz_overlay ]; };
+in with nixpkgs;
+stdenv.mkDerivation {
+  name = "moz_overlay_shell";
+  buildInputs = [
+    # to use the latest nightly:
+    nixpkgs.latest.rustChannels.nightly.rust
+  ];
+  shellHook = ''
+    exec zsh
+  '';
+}
diff --git a/rust.nix b/rust.nix
index 71d44fa..cc2cd8b 100644
--- a/rust.nix
+++ b/rust.nix
@@ -2,11 +2,10 @@ let
   # Pinned nixpkgs, deterministic. Last updated: 2/12/21.
   #pkgs = import (fetchTarball("https://github.com/NixOS/nixpkgs/archive/a58a0b5098f0c2a389ee70eb69422a052982d990.tar.gz")) {};
   # Rolling updates, not deterministic.
-  pkgs = import (fetchTarball "channel:nixpkgs-unstable") {};
-in
-  pkgs.mkShell {
-    buildInputs = [pkgs.cargo pkgs.rustc pkgs.zsh pkgs.bacon];
-    shellHook = ''
-      exec zsh
-    '';
-  }
+  pkgs = import (fetchTarball "channel:nixpkgs-unstable") { };
+in pkgs.mkShell {
+  buildInputs = [ pkgs.cargo pkgs.rustc pkgs.zsh pkgs.bacon ];
+  shellHook = ''
+    exec zsh
+  '';
+}