diff --git a/README.md b/README.md
index c60db66..bff7f71 100644
--- a/README.md
+++ b/README.md
@@ -425,7 +425,8 @@ plugin and a patched font (see [Nerd Fonts](https://www.nerdfonts.com/)).
 {
   "willothy/nvim-cokeline",
   dependencies = {
-    "kyazdani42/nvim-web-devicons",
+    "nvim-lua/plenary.nvim",        -- Required for v0.4.0+
+    "kyazdani42/nvim-web-devicons", -- If you want devicons
   },
   config = true
 }
@@ -440,9 +441,12 @@ require('packer').startup(function()
   -- ...
   use({
     'willothy/nvim-cokeline',
-    requires = 'kyazdani42/nvim-web-devicons', -- If you want devicons
+    requires = {
+      "nvim-lua/plenary.nvim",        -- Required for v0.4.0+
+      "kyazdani42/nvim-web-devicons", -- If you want devicons
+    },
     config = function()
-      require('cokeline').setup()
+      require("cokeline").setup()
     end
   })
   -- ...
@@ -457,6 +461,7 @@ If your config is still written in Vimscript and you use
 ```vim
 call plug#begin('~/.config/nvim/plugged')
   " ...
+  Plug 'nvim-lua/plenary.nvim'        " Required for v0.4.0+
   Plug 'kyazdani42/nvim-web-devicons' " If you want devicons
   Plug 'willothy/nvim-cokeline'
   " ...
diff --git a/lua/cokeline/buffers.lua b/lua/cokeline/buffers.lua
index a22c44c..a6748b4 100644
--- a/lua/cokeline/buffers.lua
+++ b/lua/cokeline/buffers.lua
@@ -8,10 +8,11 @@ local cmd = vim.cmd
 local diagnostic = vim.diagnostic or vim.lsp.diagnostic
 local fn = vim.fn
 local split = vim.split
-local filter = vim.tbl_filter
-local map = vim.tbl_map
 
 local util = require("cokeline.utils")
+local it = require("plenary.iterators")
+local iter = it.iter
+local enumerate = util.enumerate
 
 ---@type bufnr
 local current_valid_index
@@ -49,29 +50,27 @@ local M = {}
 local Buffer = {}
 Buffer.__index = Buffer
 
----@param buffers  Buffer[]
----@return Buffer[]
+---@param buffers  Iter<Buffer>
+---@return Iter<Buffer>
 local compute_unique_prefixes = function(buffers)
   local is_windows = fn.has("win32") == 1
 
-  -- FIXME: it appears in windows sometimes directories are separated by '/'
-  -- instead of '\\'??
-  if is_windows then
-    buffers = map(function(buffer)
-      buffer.path = buffer.path:gsub("/", "\\")
-      return buffer
-    end, buffers)
-  end
-
   local path_separator = not is_windows and "/" or "\\"
 
-  local paths = map(function(buffer)
-    return fn.reverse(split(buffer.path, path_separator))
-  end, buffers)
-
-  local prefixes = map(function()
-    return {}
-  end, buffers)
+  local prefixes = {}
+  local paths = {}
+  buffers = buffers
+    :map(function(buffer)
+      prefixes[#prefixes + 1] = {}
+      paths[#paths + 1] = fn.reverse(
+        split(
+          is_windows and buffer.path:gsub("/", "\\") or buffer.path,
+          path_separator
+        )
+      )
+      return buffer
+    end)
+    :tolist()
 
   for i = 1, #paths do
     for j = i + 1, #paths do
@@ -88,15 +87,14 @@ local compute_unique_prefixes = function(buffers)
     end
   end
 
-  for i, buffer in ipairs(buffers) do
+  return enumerate(iter(buffers)):map(function(i, buffer)
     buffer.unique_prefix = concat({
       #prefixes[i] == #paths[i] and path_separator or "",
       fn.join(fn.reverse(prefixes[i]), path_separator),
       #prefixes[i] > 0 and path_separator or "",
     })
-  end
-
-  return buffers
+    return i, buffer
+  end)
 end
 
 ---@param filename  string
@@ -397,45 +395,38 @@ function M.get_valid_buffers()
     _G.cokeline.buf_order = {}
   end
 
-  local buffers
   local info = fn.getbufinfo({ buflisted = 1 })
-  if vim.iter then
-    buffers = vim
-      .iter(info)
-      :map(Buffer.new)
-      :filter(function(buffer)
-        return buffer.filetype ~= "netrw"
-      end)
-      :filter(
-        type(_G.cokeline.config.buffers.filter_valid) == "function"
-            and _G.cokeline.config.buffers.filter_valid
-          or function()
-            return true
-          end
-      )
-      :totable()
-  else
-    buffers = map(Buffer.new, info)
-    buffers = filter(function(buffer)
-      return buffer.filetype ~= "netrw"
-    end, buffers)
-
-    if _G.cokeline.config.buffers.filter_valid then
-      buffers = filter(_G.cokeline.config.buffers.filter_valid, buffers)
-    end
+  ---@type Iter<Buffer>
+  local buffers = iter(info):map(Buffer.new):filter(function(buffer)
+    return buffer.filetype ~= "netrw"
+  end)
+
+  if _G.cokeline.config.buffers.filter_valid then
+    ---@type Iter<Buffer>
+    buffers = buffers:filter(_G.cokeline.config.buffers.filter_valid)
   end
 
+  ---@type Buffer[]
   buffers = compute_unique_prefixes(buffers)
 
   if current_valid_index == nil then
     _G.cokeline.buf_order = {}
-    for i, buffer in ipairs(buffers) do
-      buffer._valid_index = i
-      _G.cokeline.buf_order[buffer.number] = buffer._valid_index
-      if buffer.is_focused then
-        current_valid_index = i
-      end
-    end
+    buffers = buffers
+      :map(function(i, buffer)
+        buffer._valid_index = i
+        _G.cokeline.buf_order[buffer.number] = buffer._valid_index
+        if buffer.is_focused then
+          current_valid_index = i
+        end
+        return buffer
+      end)
+      :tolist()
+  else
+    buffers = buffers
+      :map(function(_, buf)
+        return buf
+      end)
+      :tolist()
   end
 
   if _G.cokeline.config.buffers.new_buffers_position == "last" then
@@ -465,29 +456,35 @@ end
 function M.get_visible()
   _G.cokeline.valid_buffers = M.get_valid_buffers()
   _G.cokeline.valid_lookup = {}
-  for _, buffer in ipairs(_G.cokeline.valid_buffers) do
+
+  local bufs = iter(_G.cokeline.valid_buffers):map(function(buffer)
     _G.cokeline.valid_lookup[buffer.number] = buffer
+    return buffer
+  end)
+
+  if _G.cokeline.config.buffers.filter_visible then
+    bufs = bufs:filter(_G.cokeline.config.buffers.filter_visible)
+  end
+
+  bufs = enumerate(bufs):map(function(i, buf)
+    buf.index = i
+    return buf
+  end)
+
+  if not _G.cokeline.config.pick.use_filename then
+    bufs = bufs:map(function(buf)
+      buf.pick_letter = get_pick_letter(buf.filename, buf.number)
+      return buf
+    end)
   end
 
-  _G.cokeline.visible_buffers = not _G.cokeline.config.buffers.filter_visible
-      and _G.cokeline.valid_buffers
-    or filter(
-      _G.cokeline.config.buffers.filter_visible,
-      _G.cokeline.valid_buffers
-    )
+  _G.cokeline.visible_buffers = bufs:tolist()
 
   if #_G.cokeline.visible_buffers > 0 then
     _G.cokeline.visible_buffers[1].is_first = true
     _G.cokeline.visible_buffers[#_G.cokeline.visible_buffers].is_last = true
   end
 
-  for i, buffer in ipairs(_G.cokeline.visible_buffers) do
-    buffer.index = i
-    if not _G.cokeline.config.pick.use_filename then
-      buffer.pick_letter = get_pick_letter(buffer.filename, buffer.number)
-    end
-  end
-
   return _G.cokeline.visible_buffers
 end
 
diff --git a/lua/cokeline/components.lua b/lua/cokeline/components.lua
index 6bbadc3..9cefed7 100644
--- a/lua/cokeline/components.lua
+++ b/lua/cokeline/components.lua
@@ -1,12 +1,12 @@
 local Hlgroup = require("cokeline/hlgroups").Hlgroup
 
 local rep = string.rep
-local concat = table.concat
 local insert = table.insert
 local remove = table.remove
 
+local fold = require("cokeline.utils").fold
+local iter = require("plenary.iterators").iter
 local fn = vim.fn
-local map = vim.tbl_map
 
 ---@generic Cx
 ---@class Component<Cx>
@@ -162,11 +162,9 @@ end
 ---@param components  Component[]
 ---@return number
 local width_of_components = function(components)
-  local width = 0
-  for _, component in pairs(components) do
-    width = width + component.width
-  end
-  return width
+  return fold(iter(components), 0, function(a, c)
+    return a + c.width
+  end)
 end
 
 -- Takes a list of components, returns a new list of components `to_width` wide
@@ -177,10 +175,7 @@ end
 ---@param direction  '"left"' | '"right"' | nil
 ---@return Component<Cx>[]
 local shorten_components = function(components, to_width, direction)
-  local current_width = 0
-  for _, component in pairs(components) do
-    current_width = current_width + component.width
-  end
+  local current_width = width_of_components(components)
 
   -- `extra` is the width of the extra characters that are appended when a
   -- component is shortened, an ellipses if we're shortening within a buffer
@@ -256,11 +251,12 @@ local render_components = function(components)
     end
   end
 
-  return concat(map(function(component)
-    return embed(component)
-  end, components))
-end
+  local concat = function(a, b)
+    return a .. b
+  end
 
+  return fold(iter(components):map(embed), "", concat)
+end
 
 return {
   Component = Component,
diff --git a/lua/cokeline/hover.lua b/lua/cokeline/hover.lua
index cce906f..2ff6837 100644
--- a/lua/cokeline/hover.lua
+++ b/lua/cokeline/hover.lua
@@ -5,6 +5,8 @@ local version = vim.version()
 local buffers = require("cokeline.buffers")
 local tabs = require("cokeline.tabs")
 local rendering = require("cokeline.rendering")
+local iter = require("plenary.iterators").iter
+local fold = require("cokeline.utils").fold
 local last_position = nil
 
 function M.hovered()
@@ -183,17 +185,19 @@ local function on_hover(current)
 end
 
 local function width(bufs, buf)
-  return vim
-    .iter(bufs)
-    :filter(function(v)
-      return v.bufnr == buf
-    end)
-    :map(function(v)
-      return v.width
-    end)
-    :fold(0, function(acc, v)
+  return fold(
+    iter(bufs)
+      :filter(function(v)
+        return v.bufnr == buf
+      end)
+      :map(function(v)
+        return v.width
+      end),
+    0,
+    function(acc, v)
       return acc + v
-    end)
+    end
+  )
 end
 
 local function start_pos(bufs, buf)
diff --git a/lua/cokeline/init.lua b/lua/cokeline/init.lua
index 60dabfd..a351acd 100644
--- a/lua/cokeline/init.lua
+++ b/lua/cokeline/init.lua
@@ -55,6 +55,13 @@ _G.cokeline = {
 --@param preferences table|nil
 ---@param preferences Component<TabPage>
 local setup = function(preferences)
+  local ok, _ = pcall(require, "plenary")
+  if not ok then
+    vim.api.nvim_err_writeln(
+      "nvim-cokeline: plenary.nvim is required to use this plugin as of v0.4.0"
+    )
+    return
+  end
   _G.cokeline.config = config.get(preferences or {})
   if _G.cokeline.config.history.enabled then
     history.setup(_G.cokeline.config.history.size)
diff --git a/lua/cokeline/rendering.lua b/lua/cokeline/rendering.lua
index 43b8573..2d6bd6d 100644
--- a/lua/cokeline/rendering.lua
+++ b/lua/cokeline/rendering.lua
@@ -3,13 +3,13 @@ local sidebar = require("cokeline/sidebar")
 local rhs = require("cokeline/rhs")
 local tabs = require("cokeline.tabs")
 local RenderContext = require("cokeline/context")
+local iter = require("plenary.iterators").iter
 
 local insert = table.insert
 local sort = table.sort
 local unpack = unpack or table.unpack
 
 local extend = vim.list_extend
-local filter = vim.tbl_filter
 local o = vim.o
 
 ---@type index
@@ -19,9 +19,9 @@ local current_index
 ---@param previous_buffer_index  index
 ---@return Buffer
 local find_current_buffer = function(buffers, previous_buffer_index)
-  local focused_buffer = filter(function(buffer)
+  local focused_buffer = iter(buffers):find(function(buffer)
     return buffer.is_focused
-  end, buffers)[1]
+  end)
 
   return focused_buffer or buffers[previous_buffer_index] or buffers[#buffers]
 end
diff --git a/lua/cokeline/utils.lua b/lua/cokeline/utils.lua
index 8d4fd76..2def0d8 100644
--- a/lua/cokeline/utils.lua
+++ b/lua/cokeline/utils.lua
@@ -120,7 +120,24 @@ local function buf_delete(bufnr, focus, wipeout)
   end
 end
 
+local fold = function(iterable, acc, f)
+  iterable:for_each(function(v)
+    acc = f(acc, v)
+  end)
+  return acc
+end
+
+local enumerate = function(iterable)
+  local i = 0
+  return iterable:map(function(...)
+    i = i + 1
+    return i, ...
+  end)
+end
+
 return {
   get_hex = get_hex,
   buf_delete = buf_delete,
+  fold = fold,
+  enumerate = enumerate,
 }