diff --git a/.github/ci/run_sanitizer.sh b/.github/ci/run_sanitizer.sh
index 9f6fd3580d..fb99839006 100644
--- a/.github/ci/run_sanitizer.sh
+++ b/.github/ci/run_sanitizer.sh
@@ -15,7 +15,7 @@ if git diff --pickaxe-all -U0 -G "${SEARCH_PATTERN}" "${REF_BRANCH}" "${PR_BRANC
   exit 1
 fi
 
-SEARCH_PATTERN='(util\.path\.dirname|util\.path\.sanitize|util\.path\.exists|util\.path\.is_file|util\.path\.is_dir|util\.find_mercurial_ancestor|util\.find_node_modules_ancestor|util\.find_package_json_ancestor)'
+SEARCH_PATTERN='(util\.path\.dirname|util\.path\.sanitize|util\.path\.exists|util\.path\.is_file|util\.path\.is_dir|util\.path\.is_absolute|util\.find_mercurial_ancestor|util\.find_node_modules_ancestor|util\.find_package_json_ancestor)'
 
 if git diff --pickaxe-all -U0 -G "${SEARCH_PATTERN}" "${REF_BRANCH}" "${PR_BRANCH}" -- '*.lua' | grep -Ev '\.lua$' | grep -E "^\+.*${SEARCH_PATTERN}" ; then
   echo
diff --git a/lua/lspconfig/util.lua b/lua/lspconfig/util.lua
index 4bd82b5be8..58804b030a 100644
--- a/lua/lspconfig/util.lua
+++ b/lua/lspconfig/util.lua
@@ -111,16 +111,6 @@ M.path = (function()
     end
   end
 
-  --- @param filename string
-  --- @return boolean
-  local function is_absolute(filename)
-    if iswin then
-      return filename:match '^%a:' or filename:match '^\\\\'
-    else
-      return filename:match '^/'
-    end
-  end
-
   local function path_join(...)
     return table.concat(M.tbl_flatten { ... }, '/')
   end
@@ -180,7 +170,6 @@ M.path = (function()
 
   return {
     escape_wildcards = escape_wildcards,
-    is_absolute = is_absolute,
     join = path_join,
     traverse_parents = traverse_parents,
     iterate_parents = iterate_parents,
@@ -370,6 +359,13 @@ M.path.dirname = vim.fs.dirname
 --- @deprecated use `vim.fs.normalize` instead
 M.path.sanitize = vim.fs.normalize
 
+--- @deprecated use `vim.fn.isabsolutepath(filename) == 1` instead
+--- @param filename string
+--- @return boolean
+function M.path.is_absolute(filename)
+  return vim.fn.isabsolutepath(filename) == 1
+end
+
 --- @deprecated use `vim.loop.fs_stat` instead
 --- @param filename string
 --- @return string|false
diff --git a/test/lspconfig_spec.lua b/test/lspconfig_spec.lua
index 256faba203..63a5cd9422 100644
--- a/test/lspconfig_spec.lua
+++ b/test/lspconfig_spec.lua
@@ -25,19 +25,6 @@ describe('lspconfig', function()
         end)
       end)
 
-      describe('is_absolute', function()
-        it('is absolute', function()
-          local lspconfig = require 'lspconfig'
-          eq(true, lspconfig.util.path.is_absolute '/foo/bar' ~= nil)
-        end)
-
-        it('is not absolute', function()
-          local lspconfig = require 'lspconfig'
-          assert.is_nil(lspconfig.util.path.is_absolute 'foo/bar')
-          assert.is_nil(lspconfig.util.path.is_absolute '../foo/bar')
-        end)
-      end)
-
       describe('join', function()
         it('', function()
           local lspconfig = require 'lspconfig'