diff --git a/runtime/plugin/shada.lua b/runtime/plugin/shada.lua
new file mode 100644
index 0000000000..e1517de626
--- /dev/null
+++ b/runtime/plugin/shada.lua
@@ -0,0 +1,76 @@
+if vim.g.loaded_shada_plugin then
+  return
+end
+vim.g.loaded_shada_plugin = 1
+
+local augroup = vim.api.nvim_create_augroup('nvim.shada', {})
+
+---@type fun(binstrings: string[]): string[]
+local shada_get_strings = vim.fn['shada#get_strings']
+
+---@type fun(strings: string[]): string[]
+local shada_get_binstrings = vim.fn['shada#get_binstrings']
+
+---Ensures that pattern and augroup are set correctly.
+---@param event string|string[]
+---@param opts vim.api.keyset.create_autocmd
+---@param fn fun(args: vim.api.keyset.create_autocmd.callback_args): boolean?
+local function def_autocmd(event, opts, fn)
+  opts = opts or {}
+  opts.group = augroup
+  opts.pattern = { '*.shada', '*.shada.tmp.[a-z]' }
+  opts.callback = function(ev)
+    if vim.v.cmdarg ~= '' then
+      error('++opt not supported')
+    end
+    fn(ev)
+  end
+  vim.api.nvim_create_autocmd(event, opts)
+end
+
+---Read shada strings from file.
+---@param file string Filename
+---@return string[] # lines from shada file
+local function read_strings(file)
+  local f = assert(io.open(file, 'rb'))
+  local strings = f:read('*a')
+  f:close()
+  return shada_get_strings(strings)
+end
+
+def_autocmd('BufReadCmd', {}, function(ev)
+  local lines = read_strings(ev.file)
+  vim.api.nvim_buf_set_lines(ev.buf, 0, -1, false, lines)
+  vim.bo[ev.buf].filetype = 'shada'
+end)
+
+def_autocmd('FileReadCmd', {}, function(ev)
+  local lines = read_strings(ev.file)
+  local lnum = vim.fn.line("'[")
+  vim.api.nvim_buf_set_lines(ev.buf, lnum, lnum, true, lines)
+end)
+
+def_autocmd('BufWriteCmd', {}, function(ev)
+  local buflines = vim.api.nvim_buf_get_lines(0, 0, -1, false)
+  local err = vim.fn.writefile(shada_get_binstrings(buflines), ev.file, 'b')
+  if not err then
+    vim.bo[ev.buf].modified = false
+  end
+end)
+
+def_autocmd({ 'FileWriteCmd', 'FileAppendCmd' }, {}, function(ev)
+  vim.fn.writefile(
+    shada_get_binstrings(
+      vim.fn.getline(
+        math.min(vim.fn.line("'["), vim.fn.line("']")),
+        math.max(vim.fn.line("'["), vim.fn.line("']"))
+      ) --[=[@as string[]]=]
+    ),
+    ev.file,
+    ev.event == 'FileAppendCmd' and 'ab' or 'b'
+  )
+end)
+
+def_autocmd('SourceCmd', {}, function(ev)
+  vim.cmd.rshada(vim.fn.fnameescape(ev.file))
+end)
diff --git a/runtime/plugin/shada.vim b/runtime/plugin/shada.vim
deleted file mode 100644
index 5c7d93aaa0..0000000000
--- a/runtime/plugin/shada.vim
+++ /dev/null
@@ -1,39 +0,0 @@
-if exists('g:loaded_shada_plugin')
-  finish
-endif
-let g:loaded_shada_plugin = 1
-
-augroup nvim.shada
-  autocmd!
-  autocmd BufReadCmd *.shada,*.shada.tmp.[a-z]
-        \ :if !empty(v:cmdarg)|throw '++opt not supported'|endif
-        \ |call setline('.', shada#get_strings(readfile(expand('<afile>'),'b')))
-        \ |setlocal filetype=shada
-  autocmd FileReadCmd *.shada,*.shada.tmp.[a-z]
-        \ :if !empty(v:cmdarg)|throw '++opt not supported'|endif
-        \ |call append("'[", shada#get_strings(readfile(expand('<afile>'), 'b')))
-  autocmd BufWriteCmd *.shada,*.shada.tmp.[a-z]
-        \ :if !empty(v:cmdarg)|throw '++opt not supported'|endif
-        \ |if writefile(shada#get_binstrings(getline(1, '$')),
-                       \expand('<afile>'), 'b') == 0
-        \ |  let &l:modified = (expand('<afile>') is# bufname(+expand('<abuf>'))
-                               \? 0
-                               \: stridx(&cpoptions, '+') != -1)
-        \ |endif
-  autocmd FileWriteCmd *.shada,*.shada.tmp.[a-z]
-        \ :if !empty(v:cmdarg)|throw '++opt not supported'|endif
-        \ |call writefile(
-              \shada#get_binstrings(getline(min([line("'["), line("']")]),
-                                           \max([line("'["), line("']")]))),
-              \expand('<afile>'),
-              \'b')
-  autocmd FileAppendCmd *.shada,*.shada.tmp.[a-z]
-        \ :if !empty(v:cmdarg)|throw '++opt not supported'|endif
-        \ |call writefile(
-              \shada#get_binstrings(getline(min([line("'["), line("']")]),
-                                           \max([line("'["), line("']")]))),
-              \expand('<afile>'),
-              \'ab')
-  autocmd SourceCmd *.shada,*.shada.tmp.[a-z]
-        \ :execute 'rshada' fnameescape(expand('<afile>'))
-augroup END
diff --git a/test/functional/plugin/shada_spec.lua b/test/functional/plugin/shada_spec.lua
index 26af1a127a..58b33a21ec 100644
--- a/test/functional/plugin/shada_spec.lua
+++ b/test/functional/plugin/shada_spec.lua
@@ -2664,7 +2664,12 @@ describe('plugin/shada.vim', function()
     }, nvim_eval('getline(1, "$")'))
     eq(false, api.nvim_get_option_value('modified', {}))
     eq('shada', api.nvim_get_option_value('filetype', {}))
-    eq('++opt not supported', exc_exec('edit ++enc=latin1 ' .. fname))
+    t.matches(
+      '++opt not supported',
+      t.pcall_err(function()
+        nvim_command('edit ++enc=latin1 ' .. fname)
+      end)
+    )
     neq({
       'History entry with timestamp ' .. epoch .. ':',
       '  @ Description_  Value',
@@ -2707,7 +2712,12 @@ describe('plugin/shada.vim', function()
     eq(true, api.nvim_get_option_value('modified', {}))
     neq('shada', api.nvim_get_option_value('filetype', {}))
     api.nvim_set_option_value('modified', false, {})
-    eq('++opt not supported', exc_exec('$read ++enc=latin1 ' .. fname))
+    t.matches(
+      '++opt not supported',
+      t.pcall_err(function()
+        nvim_command('$read ++enc=latin1 ' .. fname)
+      end)
+    )
     eq({
       '',
       'History entry with timestamp ' .. epoch .. ':',
@@ -2744,7 +2754,12 @@ describe('plugin/shada.vim', function()
     nvim_command('w ' .. fname .. '.tst')
     nvim_command('w ' .. fname)
     nvim_command('w ' .. fname_tmp)
-    eq('++opt not supported', exc_exec('w! ++enc=latin1 ' .. fname))
+    t.matches(
+      '++opt not supported',
+      t.pcall_err(function()
+        nvim_command('w! ++enc=latin1 ' .. fname)
+      end)
+    )
     eq(table.concat({
       'Jump with timestamp ' .. epoch .. ':',
       '  % Key________  Description  Value',
@@ -2805,7 +2820,12 @@ describe('plugin/shada.vim', function()
     nvim_command('1,3w ' .. fname .. '.tst')
     nvim_command('1,3w ' .. fname)
     nvim_command('1,3w ' .. fname_tmp)
-    eq('++opt not supported', exc_exec('1,3w! ++enc=latin1 ' .. fname))
+    t.matches(
+      '++opt not supported',
+      t.pcall_err(function()
+        nvim_command('1,3w! ++enc=latin1 ' .. fname)
+      end)
+    )
     eq(table.concat({
       'Jump with timestamp ' .. epoch .. ':',
       '  % Key________  Description  Value',
@@ -2855,7 +2875,12 @@ describe('plugin/shada.vim', function()
     nvim_command('w >> ' .. fname .. '.tst')
     nvim_command('w >> ' .. fname)
     nvim_command('w >> ' .. fname_tmp)
-    eq('++opt not supported', exc_exec('1,3w! ++enc=latin1 >> ' .. fname))
+    t.matches(
+      '++opt not supported',
+      t.pcall_err(function()
+        nvim_command('1,3w! ++enc=latin1 >> ' .. fname)
+      end)
+    )
     eq(table.concat({
       'Jump with timestamp ' .. epoch .. ':',
       '  % Key________  Description  Value',