diff --git a/runtime/lua/vim/_inspector.lua b/runtime/lua/vim/_inspector.lua
index a09dd55a47..15b0733671 100644
--- a/runtime/lua/vim/_inspector.lua
+++ b/runtime/lua/vim/_inspector.lua
@@ -53,7 +53,7 @@ function vim.inspect_pos(bufnr, row, col, filter)
     local cursor = vim.api.nvim_win_get_cursor(win)
     row, col = cursor[1] - 1, cursor[2]
   end
-  bufnr = bufnr == 0 and vim.api.nvim_get_current_buf() or bufnr
+  bufnr = vim._resolve_bufnr(bufnr)
 
   local results = {
     treesitter = {}, --- @type table[]
diff --git a/runtime/lua/vim/diagnostic.lua b/runtime/lua/vim/diagnostic.lua
index b8ffb26377..340bca4f6b 100644
--- a/runtime/lua/vim/diagnostic.lua
+++ b/runtime/lua/vim/diagnostic.lua
@@ -573,13 +573,6 @@ local underline_highlight_map = make_highlight_map('Underline')
 local floating_highlight_map = make_highlight_map('Floating')
 local sign_highlight_map = make_highlight_map('Sign')
 
-local function get_bufnr(bufnr)
-  if not bufnr or bufnr == 0 then
-    return api.nvim_get_current_buf()
-  end
-  return bufnr
-end
-
 --- @param diagnostics vim.Diagnostic[]
 --- @return table<integer,vim.Diagnostic[]>
 local function diagnostic_lines(diagnostics)
@@ -642,7 +635,7 @@ end
 --- @param namespace integer
 --- @param bufnr? integer
 local function save_extmarks(namespace, bufnr)
-  bufnr = get_bufnr(bufnr)
+  bufnr = vim._resolve_bufnr(bufnr)
   if not diagnostic_attached_buffers[bufnr] then
     api.nvim_buf_attach(bufnr, false, {
       on_lines = function(_, _, _, _, _, last)
@@ -814,7 +807,7 @@ local function get_diagnostics(bufnr, opts, clamp)
       end
     end
   elseif namespace == nil then
-    bufnr = get_bufnr(bufnr)
+    bufnr = vim._resolve_bufnr(bufnr)
     for iter_namespace in pairs(diagnostic_cache[bufnr]) do
       add_all_diags(bufnr, diagnostic_cache[bufnr][iter_namespace])
     end
@@ -825,7 +818,7 @@ local function get_diagnostics(bufnr, opts, clamp)
       end
     end
   else
-    bufnr = get_bufnr(bufnr)
+    bufnr = vim._resolve_bufnr(bufnr)
     for _, iter_namespace in ipairs(namespace) do
       add_all_diags(bufnr, diagnostic_cache[bufnr][iter_namespace] or {})
     end
@@ -1100,7 +1093,7 @@ function M.set(namespace, bufnr, diagnostics, opts)
   vim.validate('diagnostics', diagnostics, vim.islist, 'a list of diagnostics')
   vim.validate('opts', opts, 'table', true)
 
-  bufnr = get_bufnr(bufnr)
+  bufnr = vim._resolve_bufnr(bufnr)
 
   if vim.tbl_isempty(diagnostics) then
     diagnostic_cache[bufnr][namespace] = nil
@@ -1380,7 +1373,7 @@ M.handlers.signs = {
     vim.validate('diagnostics', diagnostics, vim.islist, 'a list of diagnostics')
     vim.validate('opts', opts, 'table', true)
 
-    bufnr = get_bufnr(bufnr)
+    bufnr = vim._resolve_bufnr(bufnr)
     opts = opts or {}
 
     if not api.nvim_buf_is_loaded(bufnr) then
@@ -1486,7 +1479,7 @@ M.handlers.underline = {
     vim.validate('diagnostics', diagnostics, vim.islist, 'a list of diagnostics')
     vim.validate('opts', opts, 'table', true)
 
-    bufnr = get_bufnr(bufnr)
+    bufnr = vim._resolve_bufnr(bufnr)
     opts = opts or {}
 
     if not vim.api.nvim_buf_is_loaded(bufnr) then
@@ -1550,7 +1543,7 @@ M.handlers.virtual_text = {
     vim.validate('diagnostics', diagnostics, vim.islist, 'a list of diagnostics')
     vim.validate('opts', opts, 'table', true)
 
-    bufnr = get_bufnr(bufnr)
+    bufnr = vim._resolve_bufnr(bufnr)
     opts = opts or {}
 
     if not vim.api.nvim_buf_is_loaded(bufnr) then
@@ -1675,7 +1668,7 @@ function M.hide(namespace, bufnr)
   vim.validate('namespace', namespace, 'number', true)
   vim.validate('bufnr', bufnr, 'number', true)
 
-  local buffers = bufnr and { get_bufnr(bufnr) } or vim.tbl_keys(diagnostic_cache)
+  local buffers = bufnr and { vim._resolve_bufnr(bufnr) } or vim.tbl_keys(diagnostic_cache)
   for _, iter_bufnr in ipairs(buffers) do
     local namespaces = namespace and { namespace } or vim.tbl_keys(diagnostic_cache[iter_bufnr])
     for _, iter_namespace in ipairs(namespaces) do
@@ -1702,7 +1695,7 @@ function M.is_enabled(filter)
     return vim.tbl_isempty(diagnostic_disabled) and not diagnostic_disabled[1]
   end
 
-  local bufnr = get_bufnr(filter.bufnr)
+  local bufnr = vim._resolve_bufnr(filter.bufnr)
   if type(diagnostic_disabled[bufnr]) == 'table' then
     return not diagnostic_disabled[bufnr][filter.ns_id]
   end
@@ -1743,7 +1736,7 @@ function M.show(namespace, bufnr, diagnostics, opts)
       end
     else
       -- namespace is nil
-      bufnr = get_bufnr(bufnr)
+      bufnr = vim._resolve_bufnr(bufnr)
       for iter_namespace in pairs(diagnostic_cache[bufnr]) do
         M.show(iter_namespace, bufnr, nil, opts)
       end
@@ -1810,7 +1803,7 @@ function M.open_float(opts, ...)
   end
 
   opts = opts or {}
-  bufnr = get_bufnr(bufnr or opts.bufnr)
+  bufnr = vim._resolve_bufnr(bufnr or opts.bufnr)
 
   do
     -- Resolve options with user settings from vim.diagnostic.config
@@ -2013,7 +2006,7 @@ function M.reset(namespace, bufnr)
   vim.validate('namespace', namespace, 'number', true)
   vim.validate('bufnr', bufnr, 'number', true)
 
-  local buffers = bufnr and { get_bufnr(bufnr) } or vim.tbl_keys(diagnostic_cache)
+  local buffers = bufnr and { vim._resolve_bufnr(bufnr) } or vim.tbl_keys(diagnostic_cache)
   for _, iter_bufnr in ipairs(buffers) do
     local namespaces = namespace and { namespace } or vim.tbl_keys(diagnostic_cache[iter_bufnr])
     for _, iter_namespace in ipairs(namespaces) do
@@ -2151,7 +2144,7 @@ function M.enable(enable, filter)
       ns.disabled = not enable
     end
   else
-    bufnr = get_bufnr(bufnr)
+    bufnr = vim._resolve_bufnr(bufnr)
     if not ns_id then
       diagnostic_disabled[bufnr] = (not enable) and true or nil
     else
diff --git a/runtime/lua/vim/lsp.lua b/runtime/lua/vim/lsp.lua
index e1946816da..ebdc050405 100644
--- a/runtime/lua/vim/lsp.lua
+++ b/runtime/lua/vim/lsp.lua
@@ -89,18 +89,6 @@ lsp._request_name_to_capability = {
 
 -- TODO improve handling of scratch buffers with LSP attached.
 
---- Returns the buffer number for the given {bufnr}.
----
----@param bufnr (integer|nil) Buffer number to resolve. Defaults to current buffer
----@return integer bufnr
-local function resolve_bufnr(bufnr)
-  validate('bufnr', bufnr, 'number', true)
-  if bufnr == nil or bufnr == 0 then
-    return api.nvim_get_current_buf()
-  end
-  return bufnr
-end
-
 ---@private
 --- Called by the client when trying to call a method that's not
 --- supported in any of the servers registered for the current buffer.
@@ -389,7 +377,7 @@ end
 function lsp.start(config, opts)
   opts = opts or {}
   local reuse_client = opts.reuse_client or reuse_client_default
-  local bufnr = resolve_bufnr(opts.bufnr)
+  local bufnr = vim._resolve_bufnr(opts.bufnr)
 
   for _, client in pairs(all_clients) do
     if reuse_client(client, config) then
@@ -528,7 +516,7 @@ end
 ---Buffer lifecycle handler for textDocument/didSave
 --- @param bufnr integer
 local function text_document_did_save_handler(bufnr)
-  bufnr = resolve_bufnr(bufnr)
+  bufnr = vim._resolve_bufnr(bufnr)
   local uri = vim.uri_from_bufnr(bufnr)
   local text = once(lsp._buf_get_full_text)
   for _, client in ipairs(lsp.get_clients({ bufnr = bufnr })) do
@@ -689,7 +677,7 @@ end
 function lsp.buf_attach_client(bufnr, client_id)
   validate('bufnr', bufnr, 'number', true)
   validate('client_id', client_id, 'number')
-  bufnr = resolve_bufnr(bufnr)
+  bufnr = vim._resolve_bufnr(bufnr)
   if not api.nvim_buf_is_loaded(bufnr) then
     log.warn(string.format('buf_attach_client called on unloaded buffer (id: %d): ', bufnr))
     return false
@@ -726,7 +714,7 @@ end
 function lsp.buf_detach_client(bufnr, client_id)
   validate('bufnr', bufnr, 'number', true)
   validate('client_id', client_id, 'number')
-  bufnr = resolve_bufnr(bufnr)
+  bufnr = vim._resolve_bufnr(bufnr)
 
   local client = all_clients[client_id]
   if not client or not client.attached_buffers[bufnr] then
@@ -832,7 +820,7 @@ function lsp.get_clients(filter)
 
   local clients = {} --- @type vim.lsp.Client[]
 
-  local bufnr = filter.bufnr and resolve_bufnr(filter.bufnr)
+  local bufnr = filter.bufnr and vim._resolve_bufnr(filter.bufnr)
 
   for _, client in pairs(all_clients) do
     if
@@ -928,7 +916,7 @@ function lsp.buf_request(bufnr, method, params, handler, on_unsupported)
   validate('handler', handler, 'function', true)
   validate('on_unsupported', on_unsupported, 'function', true)
 
-  bufnr = resolve_bufnr(bufnr)
+  bufnr = vim._resolve_bufnr(bufnr)
   local method_supported = false
   local clients = lsp.get_clients({ bufnr = bufnr })
   local client_request_ids = {} --- @type table<integer,integer>
@@ -1208,7 +1196,7 @@ end
 function lsp.buf_get_clients(bufnr)
   vim.deprecate('vim.lsp.buf_get_clients()', 'vim.lsp.get_clients()', '0.12')
   local result = {} --- @type table<integer,vim.lsp.Client>
-  for _, client in ipairs(lsp.get_clients({ bufnr = resolve_bufnr(bufnr) })) do
+  for _, client in ipairs(lsp.get_clients({ bufnr = vim._resolve_bufnr(bufnr) })) do
     result[client.id] = client
   end
   return result
@@ -1262,7 +1250,7 @@ function lsp.for_each_buffer_client(bufnr, fn)
     'lsp.get_clients({ bufnr = bufnr }) with regular loop',
     '0.12'
   )
-  bufnr = resolve_bufnr(bufnr)
+  bufnr = vim._resolve_bufnr(bufnr)
 
   for _, client in pairs(lsp.get_clients({ bufnr = bufnr })) do
     fn(client, client.id, bufnr)
diff --git a/runtime/lua/vim/lsp/buf.lua b/runtime/lua/vim/lsp/buf.lua
index 10479807a2..1926a0228d 100644
--- a/runtime/lua/vim/lsp/buf.lua
+++ b/runtime/lua/vim/lsp/buf.lua
@@ -519,7 +519,7 @@ end
 --- @param opts? vim.lsp.buf.format.Opts
 function M.format(opts)
   opts = opts or {}
-  local bufnr = opts.bufnr or api.nvim_get_current_buf()
+  local bufnr = vim._resolve_bufnr(opts.bufnr)
   local mode = api.nvim_get_mode().mode
   local range = opts.range
   -- Try to use visual selection if no range is given
@@ -617,7 +617,7 @@ end
 ---@param opts? vim.lsp.buf.rename.Opts Additional options:
 function M.rename(new_name, opts)
   opts = opts or {}
-  local bufnr = opts.bufnr or api.nvim_get_current_buf()
+  local bufnr = vim._resolve_bufnr(opts.bufnr)
   local clients = lsp.get_clients({
     bufnr = bufnr,
     name = opts.name,
diff --git a/runtime/lua/vim/lsp/client.lua b/runtime/lua/vim/lsp/client.lua
index 7eb023da39..e03fb2415d 100644
--- a/runtime/lua/vim/lsp/client.lua
+++ b/runtime/lua/vim/lsp/client.lua
@@ -604,18 +604,6 @@ function Client:_resolve_handler(method)
   return self.handlers[method] or lsp.handlers[method]
 end
 
---- Returns the buffer number for the given {bufnr}.
----
---- @param bufnr integer? Buffer number to resolve. Defaults to current buffer
---- @return integer bufnr
-local function resolve_bufnr(bufnr)
-  validate('bufnr', bufnr, 'number', true)
-  if bufnr == nil or bufnr == 0 then
-    return api.nvim_get_current_buf()
-  end
-  return bufnr
-end
-
 --- Sends a request to the server.
 ---
 --- This is a thin wrapper around {client.rpc.request} with some additional
@@ -640,7 +628,7 @@ function Client:request(method, params, handler, bufnr)
   end
   -- Ensure pending didChange notifications are sent so that the server doesn't operate on a stale state
   changetracking.flush(self, bufnr)
-  bufnr = resolve_bufnr(bufnr)
+  bufnr = vim._resolve_bufnr(bufnr)
   local version = lsp.util.buf_versions[bufnr]
   log.debug(self._log_prefix, 'client.request', self.id, method, params, handler, bufnr)
   local success, request_id = self.rpc.request(method, params, function(err, result)
@@ -891,7 +879,7 @@ end
 --- @param bufnr? integer
 --- @return lsp.Registration?
 function Client:_get_registration(method, bufnr)
-  bufnr = bufnr or vim.api.nvim_get_current_buf()
+  bufnr = vim._resolve_bufnr(bufnr)
   for _, reg in ipairs(self.registrations[method] or {}) do
     if not reg.registerOptions or not reg.registerOptions.documentSelector then
       return reg
@@ -928,7 +916,7 @@ end
 --- @param handler? lsp.Handler only called if a server command
 function Client:exec_cmd(command, context, handler)
   context = vim.deepcopy(context or {}, true) --[[@as lsp.HandlerContext]]
-  context.bufnr = context.bufnr or api.nvim_get_current_buf()
+  context.bufnr = vim._resolve_bufnr(context.bufnr)
   context.client_id = self.id
   local cmdname = command.command
   local fn = self.commands[cmdname] or lsp.commands[cmdname]
diff --git a/runtime/lua/vim/lsp/codelens.lua b/runtime/lua/vim/lsp/codelens.lua
index a11f84d6c6..3ccd165d0b 100644
--- a/runtime/lua/vim/lsp/codelens.lua
+++ b/runtime/lua/vim/lsp/codelens.lua
@@ -104,16 +104,12 @@ function M.run()
   end
 end
 
-local function resolve_bufnr(bufnr)
-  return bufnr == 0 and api.nvim_get_current_buf() or bufnr
-end
-
 --- Clear the lenses
 ---
 ---@param client_id integer|nil filter by client_id. All clients if nil
 ---@param bufnr integer|nil filter by buffer. All buffers if nil, 0 for current buffer
 function M.clear(client_id, bufnr)
-  bufnr = bufnr and resolve_bufnr(bufnr)
+  bufnr = bufnr and vim._resolve_bufnr(bufnr)
   local buffers = bufnr and { bufnr }
     or vim.tbl_filter(api.nvim_buf_is_loaded, api.nvim_list_bufs())
   for _, iter_bufnr in pairs(buffers) do
@@ -296,7 +292,7 @@ end
 --- @param opts? vim.lsp.codelens.refresh.Opts Optional fields
 function M.refresh(opts)
   opts = opts or {}
-  local bufnr = opts.bufnr and resolve_bufnr(opts.bufnr)
+  local bufnr = opts.bufnr and vim._resolve_bufnr(opts.bufnr)
   local buffers = bufnr and { bufnr }
     or vim.tbl_filter(api.nvim_buf_is_loaded, api.nvim_list_bufs())
 
diff --git a/runtime/lua/vim/lsp/completion.lua b/runtime/lua/vim/lsp/completion.lua
index 1e950f625e..dbf0a62eeb 100644
--- a/runtime/lua/vim/lsp/completion.lua
+++ b/runtime/lua/vim/lsp/completion.lua
@@ -716,7 +716,7 @@ end
 --- @param bufnr integer Buffer handle, or 0 for the current buffer
 --- @param opts? vim.lsp.completion.BufferOpts
 function M.enable(enable, client_id, bufnr, opts)
-  bufnr = (bufnr == 0 and api.nvim_get_current_buf()) or bufnr
+  bufnr = vim._resolve_bufnr(bufnr)
 
   if enable then
     enable_completions(client_id, bufnr, opts or {})
diff --git a/runtime/lua/vim/lsp/diagnostic.lua b/runtime/lua/vim/lsp/diagnostic.lua
index 3f135d84f3..9a879d9f38 100644
--- a/runtime/lua/vim/lsp/diagnostic.lua
+++ b/runtime/lua/vim/lsp/diagnostic.lua
@@ -356,9 +356,7 @@ end
 ---@param bufnr (integer) Buffer handle, or 0 for current
 ---@private
 function M._enable(bufnr)
-  if bufnr == nil or bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
 
   if not bufstates[bufnr] then
     bufstates[bufnr] = { enabled = true }
diff --git a/runtime/lua/vim/lsp/inlay_hint.lua b/runtime/lua/vim/lsp/inlay_hint.lua
index f1a58de621..50cf9f5f29 100644
--- a/runtime/lua/vim/lsp/inlay_hint.lua
+++ b/runtime/lua/vim/lsp/inlay_hint.lua
@@ -149,8 +149,8 @@ function M.get(filter)
       vim.list_extend(hints, M.get(vim.tbl_extend('keep', { bufnr = buf }, filter)))
     end, vim.api.nvim_list_bufs())
     return hints
-  elseif bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
+  else
+    bufnr = vim._resolve_bufnr(bufnr)
   end
 
   local bufstate = bufstates[bufnr]
@@ -203,9 +203,7 @@ end
 --- Clear inlay hints
 ---@param bufnr (integer) Buffer handle, or 0 for current
 local function clear(bufnr)
-  if bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
   local bufstate = bufstates[bufnr]
   local client_lens = (bufstate or {}).client_hints or {}
   local client_ids = vim.tbl_keys(client_lens) --- @type integer[]
@@ -221,9 +219,7 @@ end
 --- Disable inlay hints for a buffer
 ---@param bufnr (integer) Buffer handle, or 0 for current
 local function _disable(bufnr)
-  if bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
   clear(bufnr)
   bufstates[bufnr] = nil
   bufstates[bufnr].enabled = false
@@ -242,9 +238,7 @@ end
 --- Enable inlay hints for a buffer
 ---@param bufnr (integer) Buffer handle, or 0 for current
 local function _enable(bufnr)
-  if bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
   bufstates[bufnr] = nil
   bufstates[bufnr].enabled = true
   _refresh(bufnr)
@@ -371,13 +365,10 @@ function M.is_enabled(filter)
   filter = filter or {}
   local bufnr = filter.bufnr
 
-  vim.validate('bufnr', bufnr, 'number', true)
   if bufnr == nil then
     return globalstate.enabled
-  elseif bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
   end
-  return bufstates[bufnr].enabled
+  return bufstates[vim._resolve_bufnr(bufnr)].enabled
 end
 
 --- Optional filters |kwargs|, or `nil` for all.
diff --git a/runtime/lua/vim/lsp/semantic_tokens.lua b/runtime/lua/vim/lsp/semantic_tokens.lua
index 01421fea29..7cc3f95aed 100644
--- a/runtime/lua/vim/lsp/semantic_tokens.lua
+++ b/runtime/lua/vim/lsp/semantic_tokens.lua
@@ -600,9 +600,7 @@ function M.start(bufnr, client_id, opts)
   vim.validate('bufnr', bufnr, 'number')
   vim.validate('client_id', client_id, 'number')
 
-  if bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
 
   opts = opts or {}
   assert(
@@ -655,9 +653,7 @@ function M.stop(bufnr, client_id)
   vim.validate('bufnr', bufnr, 'number')
   vim.validate('client_id', client_id, 'number')
 
-  if bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
 
   local highlighter = STHighlighter.active[bufnr]
   if not highlighter then
@@ -691,9 +687,7 @@ end
 ---        - modifiers (table) token modifiers as a set. E.g., { static = true, readonly = true }
 ---        - client_id (integer)
 function M.get_at_pos(bufnr, row, col)
-  if bufnr == nil or bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
 
   local highlighter = STHighlighter.active[bufnr]
   if not highlighter then
@@ -739,8 +733,7 @@ function M.force_refresh(bufnr)
   vim.validate('bufnr', bufnr, 'number', true)
 
   local buffers = bufnr == nil and vim.tbl_keys(STHighlighter.active)
-    or bufnr == 0 and { api.nvim_get_current_buf() }
-    or { bufnr }
+    or { vim._resolve_bufnr(bufnr) }
 
   for _, buffer in ipairs(buffers) do
     local highlighter = STHighlighter.active[buffer]
@@ -770,9 +763,7 @@ end
 ---@param hl_group (string) Highlight group name
 ---@param opts? vim.lsp.semantic_tokens.highlight_token.Opts  Optional parameters:
 function M.highlight_token(token, bufnr, client_id, hl_group, opts)
-  if bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
   local highlighter = STHighlighter.active[bufnr]
   if not highlighter then
     return
diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 5bf436f2ca..6bee5bc31f 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -192,9 +192,7 @@ local function get_lines(bufnr, rows)
   rows = type(rows) == 'table' and rows or { rows }
 
   -- This is needed for bufload and bufloaded
-  if bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
 
   local function buf_lines()
     local lines = {} --- @type table<integer,string>
@@ -1976,7 +1974,7 @@ function M.make_given_range_params(start_pos, end_pos, bufnr, position_encoding)
   validate('start_pos', start_pos, 'table', true)
   validate('end_pos', end_pos, 'table', true)
   validate('position_encoding', position_encoding, 'string', true)
-  bufnr = bufnr or api.nvim_get_current_buf()
+  bufnr = vim._resolve_bufnr(bufnr)
   if position_encoding == nil then
     vim.notify_once(
       'position_encoding param is required in vim.lsp.util.make_given_range_params. Defaulting to position encoding of the first client.',
@@ -2143,10 +2141,7 @@ end
 ---@param opts? vim.lsp.util._refresh.Opts Options table
 function M._refresh(method, opts)
   opts = opts or {}
-  local bufnr = opts.bufnr
-  if bufnr == nil or bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  local bufnr = vim._resolve_bufnr(opts.bufnr)
 
   local clients = vim.lsp.get_clients({ bufnr = bufnr, method = method, id = opts.client_id })
 
diff --git a/runtime/lua/vim/shared.lua b/runtime/lua/vim/shared.lua
index 2e8edea22a..9314d34314 100644
--- a/runtime/lua/vim/shared.lua
+++ b/runtime/lua/vim/shared.lua
@@ -1399,4 +1399,14 @@ function vim._with(context, f)
   return vim._with_c(context, callback)
 end
 
+--- @param bufnr? integer
+--- @return integer
+function vim._resolve_bufnr(bufnr)
+  if bufnr == nil or bufnr == 0 then
+    return vim.api.nvim_get_current_buf()
+  end
+  vim.validate('bufnr', bufnr, 'number')
+  return bufnr
+end
+
 return vim
diff --git a/runtime/lua/vim/treesitter.lua b/runtime/lua/vim/treesitter.lua
index dca89f413c..5f4e796413 100644
--- a/runtime/lua/vim/treesitter.lua
+++ b/runtime/lua/vim/treesitter.lua
@@ -32,9 +32,7 @@ M.minimum_language_version = vim._ts_get_minimum_language_version()
 ---
 ---@return vim.treesitter.LanguageTree object to use for parsing
 function M._create_parser(bufnr, lang, opts)
-  if bufnr == 0 then
-    bufnr = vim.api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
 
   vim.fn.bufload(bufnr)
 
@@ -90,9 +88,7 @@ function M.get_parser(bufnr, lang, opts)
   opts = opts or {}
   local should_error = opts.error == nil or opts.error
 
-  if bufnr == nil or bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
 
   if not valid_lang(lang) then
     lang = M.language.get_lang(vim.bo[bufnr].filetype)
@@ -258,9 +254,7 @@ end
 ---
 ---@return {capture: string, lang: string, metadata: vim.treesitter.query.TSMetadata}[]
 function M.get_captures_at_pos(bufnr, row, col)
-  if bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  bufnr = vim._resolve_bufnr(bufnr)
   local buf_highlighter = M.highlighter.active[bufnr]
 
   if not buf_highlighter then
@@ -361,11 +355,7 @@ end
 function M.get_node(opts)
   opts = opts or {}
 
-  local bufnr = opts.bufnr
-
-  if not bufnr or bufnr == 0 then
-    bufnr = api.nvim_get_current_buf()
-  end
+  local bufnr = vim._resolve_bufnr(opts.bufnr)
 
   local row, col --- @type integer, integer
   if opts.pos then
@@ -417,7 +407,7 @@ end
 ---@param bufnr (integer|nil) Buffer to be highlighted (default: current buffer)
 ---@param lang (string|nil) Language of the parser (default: from buffer filetype)
 function M.start(bufnr, lang)
-  bufnr = bufnr or api.nvim_get_current_buf()
+  bufnr = vim._resolve_bufnr(bufnr)
   local parser = assert(M.get_parser(bufnr, lang, { error = false }))
   M.highlighter.new(parser)
 end
@@ -426,7 +416,7 @@ end
 ---
 ---@param bufnr (integer|nil) Buffer to stop highlighting (default: current buffer)
 function M.stop(bufnr)
-  bufnr = (bufnr and bufnr ~= 0) and bufnr or api.nvim_get_current_buf()
+  bufnr = vim._resolve_bufnr(bufnr)
 
   if M.highlighter.active[bufnr] then
     M.highlighter.active[bufnr]:destroy()