diff --git a/darwin-configuration.nix b/darwin-configuration.nix
index 0bd4d83..1ea6058 100644
--- a/darwin-configuration.nix
+++ b/darwin-configuration.nix
@@ -2,12 +2,6 @@
 
 let python = import ./python.nix { inherit pkgs; }; in
 
-let gmp =
-  if pkgs.stdenv.isDarwin then
-      import ./gmp.nix { inherit pkgs; }
-  else pkgs.gmp
-  ; in
-
 {
 
   nix.useDaemon = true;
@@ -26,7 +20,6 @@ let gmp =
       pkgs.rustup
       pkgs.libiconv
       pkgs.clang
-      #gmp
       #pkgs.keepassxc
       python
     ];
@@ -50,12 +43,13 @@ let gmp =
 
   # Auto upgrade nix package and the daemon service.
   services.nix-daemon.enable = true;
-  nix.package = pkgs.nix;
+  nix.package = pkgs.nixFlakes;
   nix.gc.automatic = true;
   nix.useSandbox = true;
 
   nix.extraOptions = ''
     auto-optimise-store = true
+    experimental-features = nix-command flakes
   '';
 
   # Used for backwards compatibility, please read the changelog before changing.
diff --git a/gmp.nix b/gmp.nix
deleted file mode 100644
index 6d2bb9b..0000000
--- a/gmp.nix
+++ /dev/null
@@ -1,17 +0,0 @@
-{ pkgs ? import <nixpkgs> {} }:
-
-# If this fails, `chmod -R a+rw /usr/local/opt/gmp/lib`
-pkgs.runCommandLocal "gmp-symlink" {} ''
-dest="/usr/local/opt/gmp/lib/libgmp.10.dylib"
-existing=$(readlink "$dest")
-if [ $? -eq 1 ]; then
-  ln -s ${pkgs.gmp}/lib/libgmp.10.dylib "$dest" && mkdir -p $out && touch $out/done.txt
-else
-  if [[ "$existing" == /nix/store/* ]]; then
-    ln -fs ${pkgs.gmp}/lib/libgmp.10.dylib "$dest" && mkdir -p $out && touch $out/done.txt
-  else
-    echo "Existing symlink is $existing, refusing to overwrite"
-    exit 1
-  fi
-fi
-''
diff --git a/gmp/default.nix b/gmp/default.nix
new file mode 100644
index 0000000..a6cc199
--- /dev/null
+++ b/gmp/default.nix
@@ -0,0 +1,36 @@
+{ pkgs, config, lib, ... }:
+
+
+let link = ./link.sh; in
+let gmp-symlink =
+    pkgs.stdenv.mkDerivation {
+
+        name = "gmp-symlink";
+        src = ./link.sh;
+        phases = [ "unpackPhase" ];
+        unpackPhase = ''
+        mkdir -p "$out"
+        cp ${link} "$out/link.sh"
+        chmod u+x "$out/link.sh"
+        sed -i 's_NIX-GMP_${config.gmp-symlink.gmp}_' "$out/link.sh"
+        '';
+
+        installPhase = ''
+        '';
+    };
+in
+
+{
+  options = {
+    gmp-symlink.enable = lib.mkOption { default = false; };
+    gmp-symlink.gmp = lib.mkOption { default = pkgs.gmp; };
+  };
+
+  config = lib.mkIf config.gmp-symlink.enable {
+    home.activation.gmp-symlink = lib.hm.dag.entryAfter [ "writeBoundary" ] ''
+${gmp-symlink}/link.sh
+    '';
+  };
+
+}
+
diff --git a/gmp/link.sh b/gmp/link.sh
new file mode 100644
index 0000000..36fb524
--- /dev/null
+++ b/gmp/link.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+dest="/usr/local/opt/gmp/lib/libgmp.10.dylib"
+sudo mkdir -p "$(dirname "$dest")"
+existing=$(readlink "$dest")
+if [ $? -eq 1 ]; then
+  sudo ln -s "NIX-GMP/lib/libgmp.10.dylib" "$dest"
+else
+  if [[ "$existing" == /nix/store/* ]]; then
+    sudo ln -fs "NIX-GMP/lib/libgmp.10.dylib" "$dest"
+  else
+    echo "Existing symlink is $existing, refusing to overwrite"
+    exit 1
+  fi
+fi
diff --git a/home.nix b/home.nix
index 30bb41a..4f90fc7 100644
--- a/home.nix
+++ b/home.nix
@@ -4,9 +4,10 @@ let username = "Patrick"; in
 let dotnet = pkgs.dotnet-sdk_6; in
 
 {
-  imports = [ ./rider ];
+  imports = [ ./rider ./gmp ];
 
   rider = { enable = true; username = username; dotnet = dotnet; };
+  gmp-symlink = { enable = true; };
 
   # Let Home Manager install and manage itself.
   programs.home-manager.enable = true;
@@ -32,6 +33,7 @@ let dotnet = pkgs.dotnet-sdk_6; in
       pkgs.wget
       pkgs.youtube-dl
       pkgs.cmake
+      pkgs.gnumake
       pkgs.gcc
       pkgs.gdb
       pkgs.hledger
@@ -48,6 +50,7 @@ let dotnet = pkgs.dotnet-sdk_6; in
       pkgs.hugo
       #pkgs.agda
       pkgs.pijul
+      pkgs.universal-ctags
     ];
 
   programs.vscode = {
@@ -96,6 +99,7 @@ let dotnet = pkgs.dotnet-sdk_6; in
       vim = "nvim";
       view = "vim -R";
       nix-upgrade = "sudo -i sh -c 'nix-channel --update && nix-env -iA nixpkgs.nix && launchctl remove org.nixos.nix-daemon && launchctl load /Library/LaunchDaemons/org.nixos.nix-daemon.plist'";
+      cmake = "cmake -DCMAKE_MAKE_PROGRAM=${pkgs.gnumake}/bin/make";
     };
   };
 
@@ -135,6 +139,7 @@ let dotnet = pkgs.dotnet-sdk_6; in
   programs.neovim.enable = true;
   programs.neovim.plugins = with pkgs.vimPlugins; [
     molokai
+    tagbar
     { plugin = rust-vim;
       config = "let g:rustfmt_autosave = 1"; }
     { plugin = syntastic;