diff --git a/README.md b/README.md
index aa25271..fb5117c 100644
--- a/README.md
+++ b/README.md
@@ -181,14 +181,24 @@ vim.api.nvim_create_autocmd("User", {
 })
 ```
 
-## 🫂 Special Thanks
+## 🫂 Attributions / Special Thanks
 
-I extend my thanks to the awesome [Lychee](https://github.com/itslychee),
-[mrshmllow](https://github.com/mrshmllow) and
-[diniamo](https://github.com/diniamo) for their invaluable assistance in the
-creation of this plugin. I would also like to thank
-[direnv.vim](https://github.com/direnv/direnv.vim) maintainers for their initial
-work.
+[direnv.vim]: https://github.com/direnv/direnv.vim
+
+My first thanks go first to the awesome [direnv.vim] (available under the MIT
+license) that this plugin draws a lot of inspiration from. It is a small,
+practical solution that has served me well.
+
+[diniamo]: https://github.com/diniamo
+[lychee]: https://github.com/itslychee
+[mrshmllow]: https://github.com/mrshmllow
+
+I would also like to extend my thanks to
+
+I extend my thanks to the awesome [diniamo], [Lychee], [mrshmllow] for their
+invaluable assistance in the creation of this plugin. The earlier prototypes of
+this plugin were nowhere near what it is today, and thanks to them many
+improvements were made possible.
 
 ## 📜 License
 
diff --git a/ftdetect/direnv.lua b/ftdetect/direnv.lua
new file mode 100644
index 0000000..2ff3164
--- /dev/null
+++ b/ftdetect/direnv.lua
@@ -0,0 +1,9 @@
+-- Detect .envrc, .direnvrc, direnvrc files and set filetype to 'direnv'
+local group = vim.api.nvim_create_augroup("direnv_ftdetect", { clear = true })
+vim.api.nvim_create_autocmd({ "BufRead", "BufNewFile" }, {
+   group = group,
+   pattern = { ".envrc*", ".direnvrc*", "direnvrc*" },
+   callback = function()
+      vim.bo.filetype = "direnv"
+   end,
+})
diff --git a/ftplugin/direnv.lua b/ftplugin/direnv.lua
new file mode 100644
index 0000000..016c4ef
--- /dev/null
+++ b/ftplugin/direnv.lua
@@ -0,0 +1,47 @@
+if vim.b.did_ftplugin then
+   return
+end
+vim.b.did_ftplugin = true
+
+-- Set buffer-local commentstring
+vim.bo.commentstring = "# %s"
+
+-- Saving an .envrc (or related) should automatically trigger the plugin's
+-- reload/refresh behavior without causing errors when the plugin/command
+-- is not installed.
+local group = vim.api.nvim_create_augroup("DirenvBuffer", { clear = false })
+vim.api.nvim_create_autocmd("BufWritePost", {
+   group = group,
+   buffer = 0,
+   callback = function()
+      -- Trigger the Direnv reload command if available
+      if vim.fn.exists(":Direnv") == 2 then
+         pcall(vim.cmd, "Direnv reload")
+      end
+   end,
+})
+
+-- Decide whether to use tree-sitter or legacy syntax script. Tree-sitter
+-- is more modern and is almost always preferrable to Regex-based highlighting
+-- that the legacy method requires, but it's difficult to bundle a Tree-sitter
+-- grammar, so we cannot unconditionally load my own Direnv grammar. Though, if
+-- it IS available then we should skip legacy syntax highlighting.
+local has_ts = false
+local ok, parsers = pcall(require, "nvim-treesitter.parsers")
+if ok and type(parsers.has_parser) == "function" then
+   has_ts = parsers.has_parser("direnv")
+end
+
+if has_ts then
+   -- If a parser exists, prefer tree-sitter highlighting. Nothing to do
+   -- here because nvim-treesitter will attach based on filetype by itself.
+   return
+end
+
+-- Set syntax to direnv so Vim will load the bundled syntax file. Only set
+-- if no syntax is already active for this buffer, i.e., if tree-sitter is
+-- not loaded/available.
+if not vim.bo.syntax or vim.bo.syntax == "" then
+   -- setlocal syntax=direnv should cause Vim to load syntax/direnv.vim from runtime
+   pcall(vim.cmd, "setlocal syntax=direnv")
+end
diff --git a/syntax/direnv.vim b/syntax/direnv.vim
new file mode 100644
index 0000000..07e27f6
--- /dev/null
+++ b/syntax/direnv.vim
@@ -0,0 +1,89 @@
+" direnv.vim - support for direnv <http://direnv.net>
+" Author:       JINNOUCHI Yasushi <me@delphinus.dev>
+" Version:      0.2
+
+if exists('b:current_syntax')
+  finish
+endif
+
+" To use syntax for bash in sh.vim, set the g:is_bash value temporarily.
+let s:current = get(g:, 'is_bash', '__NO_VALUE__')
+let g:is_bash = 1
+runtime! syntax/sh.vim
+if s:current ==# '__NO_VALUE__'
+  unlet g:is_bash
+else
+  let g:is_bash = s:current
+endif
+unlet s:current
+
+let b:current_syntax = 'direnv'
+
+" Func: with commands {{{
+" `has` func takes one argument that represents a CLI command.
+syn keyword direnvCommandFunc has nextgroup=direnvCommand,shSingleQuote,shDoubleQuote skipwhite
+hi def link direnvCommandFunc shStatement
+
+" command name is almost the same as direnvPath, but has a different color.
+syn region direnvCommand start=/[^'"[:space:]]/ skip=/\\./ end=/\([][(){}#`'";\\[:space:]]\)\@=\|$/ contained nextgroup=shComment skipwhite
+hi def link direnvCommand shCommandSub
+" }}}
+
+" Func: with paths {{{
+" These funcs takes one argument that represents a file/dir path.
+syn keyword direnvPathFunc dotenv dotenv_if_exists env_vars_required fetchurl join_args user_rel_path on_git_branch find_up has source_env source_env_if_exists source_up source_up_if_exists source_url PATH_add MANPATH_add load_prefix watch_file watch_dir semver_search strict_env unstrict_env nextgroup=direnvPath,shSingleQuote,shDoubleQuote skipwhite
+hi def link direnvPathFunc shStatement
+
+" path string can end before non-escaped [, ], (, ), {, }, #, `, ', ", ;, \, and spaces.
+syn region direnvPath start=/[^'"[:space:]]/ skip=/\\./ end=/\([][(){}#`'";\\[:space:]]\)\@=\|$/ contained nextgroup=shComment skipwhite
+hi def link direnvPath Directory
+
+" `expand_path` takes one or two arguments that represents a dir path.
+syn keyword direnvExpandPathFunc expand_path nextgroup=direnvExpandPathRel,shSingleQuote,shDoubleQuote skipwhite
+hi def link direnvExpandPathFunc shStatement
+
+syn region direnvExpandPathRel start=/[^'"[:space:]]/ skip=/\\./ end=/\%(\s\|\_$\)/ contained nextgroup=direnvPath,shSingleQuote,shDoubleQuote skipwhite
+hi def link direnvExpandPathRel Directory
+
+" `path_add` takes two arguments that represents a variable name and a dir
+" path.
+syn keyword direnvPathAddFunc PATH_add MANPATH_add PATH_rm path_rm path_add nextgroup=direnvVar skipwhite
+hi def link direnvPathAddFunc shStatement
+
+syn match direnvVar /\S\+/ nextgroup=direnvPath,shSingleQuote,shDoubleQuote contained skipwhite
+hi def link direnvVar shCommandSub
+" }}}
+
+" Func: use {{{
+syn keyword direnvUseFunc use use_flake use_guix use_julia use_nix use_node use_nodenv use_rbenv use_vim rvm nextgroup=direnvUseCommand skipwhite
+hi def link direnvUseFunc shStatement
+
+" `use rbenv/nix/guix` takes several arguments.
+syn match direnvUseCommand /\S\+/ contained
+hi def link direnvUseCommand shCommandSub
+" }}}
+
+" Func: layout {{{
+" `layout` takes one argument that represents a language name.
+syn keyword direnvLayoutFunc layout layout_anaconda layout_go layout_julia layout_node layout_perl layout_php layout_pipenv layout_pyenv layout_python layout_python2 layout_python3 layout_ruby nextgroup=direnvLayoutLanguage,direnvLayoutLanguagePath skipwhite
+hi def link direnvLayoutFunc shStatement
+
+syn keyword direnvLayoutLanguage go node perl python3 ruby contained
+hi def link direnvLayoutLanguage shCommandSub
+
+" `layout python` takes one more argument that represents a file path.
+syn keyword direnvLayoutLanguagePath python nextgroup=direnvPath,shSingleQuote,shDoubleQuote contained skipwhite
+hi def link direnvLayoutLanguagePath shCommandSub
+" }}}
+
+" Func: others {{{
+" `direnv_load` takes several arguments.
+syn keyword direnvFunc direnv_apply_dump direnv_layout_dir direnv_load direnv_version log_error log_status
+hi def link direnvFunc shStatement
+" }}}
+
+syn cluster direnvStatement contains=direnvCommandFunc,direnvPathFunc,direnvExpandPathFunc,direnvPathAddFunc,direnvUseFunc,direnvLayoutFunc,direnvFunc
+syn cluster shArithParenList add=@direnvStatement
+syn cluster shCommandSubList add=@direnvStatement
+
+" vim:se fdm=marker: