diff --git a/lua/guard/events.lua b/lua/guard/events.lua
index 6bd8118..c1f4fd1 100644
--- a/lua/guard/events.lua
+++ b/lua/guard/events.lua
@@ -132,11 +132,12 @@ function M.try_attach_lint_to_buf(buf, events)
 end
 
 ---@param ft string
-function M.fmt_attach_to_existing(ft)
+---@param events AutocmdConfig[]?
+function M.fmt_attach_to_existing(ft, events)
   local bufs = api.nvim_list_bufs()
   for _, buf in ipairs(bufs) do
     if vim.bo[buf].ft == ft then
-      M.try_attach_fmt_to_buf(buf)
+      M.try_attach_fmt_to_buf(buf, events)
     end
   end
 end
diff --git a/lua/guard/filetype.lua b/lua/guard/filetype.lua
index 3afa2d8..e0de7b9 100644
--- a/lua/guard/filetype.lua
+++ b/lua/guard/filetype.lua
@@ -75,8 +75,11 @@ local function box(ft)
         M[it] = box(it)
         M[it].formatter = self.formatter
       end
-      events.fmt_watch_ft(it, M[it].events)
-      events.fmt_attach_to_existing(it)
+      -- BUG: maybe we want each tool to have its own events...
+      local first = M[it].formatter[1]
+      local aus = type(first) == 'table' and first.autocmds or nil
+      events.fmt_watch_ft(it, aus)
+      events.fmt_attach_to_existing(it, aus)
     end
     return self
   end
diff --git a/lua/guard/util.lua b/lua/guard/util.lua
index 58588da..f474d32 100644
--- a/lua/guard/util.lua
+++ b/lua/guard/util.lua
@@ -232,16 +232,20 @@ end
 ---@param cb function
 ---@return AutocmdOpt
 function M.au_option_copy(opt, group, cb)
-  if not opt or vim.tbl_isempty(opt) then
-    return opt
+  local t
+  if not opt or type(opt) ~= 'table' or vim.tbl_isempty(opt) then
+    t = {}
+  else
+    t = opt
   end
   return {
     group = group,
-    callback = opt.callback or cb,
-    buffer = opt.buffer,
-    nested = opt.nested,
-    once = opt.once,
-    pattern = opt.pattern,
+    callback = (not t.callback and not t.command) and cb or t.callback,
+    command = t.command,
+    buffer = t.buffer,
+    nested = t.nested,
+    once = t.once,
+    pattern = t.pattern,
   }
 end
 
diff --git a/spec/format_spec.lua b/spec/format_spec.lua
index 1211a2f..97ab3af 100644
--- a/spec/format_spec.lua
+++ b/spec/format_spec.lua
@@ -1,11 +1,16 @@
 ---@diagnostic disable: undefined-field, undefined-global
 local api = vim.api
-local equal = assert.equal
+local equal, same = assert.equal, assert.are.same
 local ft = require('guard.filetype')
 local gapi = require('guard.api')
+local group = require('guard.events').group
 
 describe('format module', function()
   local bufnr
+  local ill_lua = {
+    'local a',
+    '          = "test"',
+  }
   before_each(function()
     for k, _ in pairs(ft) do
       ft[k] = nil
@@ -15,6 +20,9 @@ describe('format module', function()
     vim.bo[bufnr].filetype = 'lua'
     api.nvim_set_current_buf(bufnr)
     vim.cmd('silent! write! /tmp/fmt_spec_test.lua')
+    vim.iter(api.nvim_get_autocmds({ group = group })):each(function(it)
+      api.nvim_del_autocmd(it.id)
+    end)
   end)
 
   it('can format with single formatter', function()
@@ -23,10 +31,7 @@ describe('format module', function()
       args = { '-' },
       stdin = true,
     })
-    api.nvim_buf_set_lines(bufnr, 0, -1, false, {
-      'local a',
-      '          = "test"',
-    })
+    api.nvim_buf_set_lines(bufnr, 0, -1, false, ill_lua)
     gapi.fmt()
     vim.wait(500)
     local line = api.nvim_buf_get_lines(bufnr, 0, -1, false)[1]
@@ -43,10 +48,7 @@ describe('format module', function()
       args = { '-s', ' ' },
       stdin = true,
     })
-    api.nvim_buf_set_lines(bufnr, 0, -1, false, {
-      'local a',
-      '          = "test"',
-    })
+    api.nvim_buf_set_lines(bufnr, 0, -1, false, ill_lua)
     gapi.fmt()
     vim.wait(500)
     local lines = api.nvim_buf_get_lines(bufnr, 0, -1, false)
@@ -59,10 +61,7 @@ describe('format module', function()
         return table.concat(vim.split(acc, '\n'), '') .. vim.inspect(range)
       end,
     })
-    api.nvim_buf_set_lines(bufnr, 0, -1, false, {
-      'local a',
-      '          = "test"',
-    })
+    api.nvim_buf_set_lines(bufnr, 0, -1, false, ill_lua)
     gapi.fmt()
     vim.wait(500)
     local lines = api.nvim_buf_get_lines(bufnr, 0, -1, false)
@@ -109,4 +108,27 @@ describe('format module', function()
     lines = api.nvim_buf_get_lines(bufnr, 0, -1, false)
     assert.are.same({ 'def' }, lines)
   end)
+
+  it('can format on custom events', function()
+    ft('lua'):fmt({
+      cmd = 'stylua',
+      args = { '-' },
+      stdin = true,
+      autocmds = {
+        { event = 'ColorScheme', opt = {} },
+      },
+    })
+
+    api.nvim_buf_set_lines(bufnr, 0, -1, false, ill_lua)
+
+    vim.cmd('silent! write! /tmp/fmt_spec_test.lua')
+    vim.wait(500)
+
+    same(ill_lua, api.nvim_buf_get_lines(bufnr, 0, -1, false))
+
+    vim.cmd.colorscheme('blue')
+    vim.wait(500)
+
+    equal([[local a = 'test']], api.nvim_buf_get_lines(bufnr, 0, -1, false)[1])
+  end)
 end)