diff --git a/ale_linters/html/tidy.vim b/ale_linters/html/tidy.vim
index 4a55d62f..34152c6b 100644
--- a/ale_linters/html/tidy.vim
+++ b/ale_linters/html/tidy.vim
@@ -25,8 +25,16 @@ function! ale_linters#html#tidy#GetCommand(buffer) abort
     \   'utf-8':        '-utf8',
     \ }, &fileencoding, '-utf8')
 
+    " On macOS, old tidy (released on 31 Oct 2006) is installed. It does not
+    " consider HTML5 so we should avoid it.
+    let l:executable = ale#Var(a:buffer, 'html_tidy_executable')
+    if has('mac') && l:executable is# 'tidy' && exists('*exepath')
+    \  && exepath(l:executable) is# '/usr/bin/tidy'
+        return ''
+    endif
+
     return printf('%s %s %s -',
-    \   ale#Var(a:buffer, 'html_tidy_executable'),
+    \   l:executable,
     \   ale#Var(a:buffer, 'html_tidy_options'),
     \   l:file_encoding
     \)
diff --git a/doc/ale-html.txt b/doc/ale-html.txt
index 14e705e0..c5d5afa5 100644
--- a/doc/ale-html.txt
+++ b/doc/ale-html.txt
@@ -32,6 +32,21 @@ g:ale_html_htmlhint_use_global                 *g:ale_html_htmlhint_use_global*
 ===============================================================================
 tidy                                                            *ale-html-tidy*
 
+`tidy` is a console application which corrects and cleans up HTML and XML
+documents by fixing markup errors and upgrading legacy code to modern
+standards.
+
+Note:
+`/usr/bin/tidy` on macOS (installed by default) is too old. It was released
+on 31 Oct 2006. It does not consider modern HTML specs (HTML5) and shows
+outdated warnings. So |ale| ignores `/usr/bin/tidy` on macOS.
+
+To use `tidy` on macOS, please install the latest version with Homebrew:
+>
+  $ brew install tidy-html5
+<
+`/usr/local/bin/tidy` is installed.
+
 g:ale_html_tidy_executable                         *g:ale_html_tidy_executable*
                                                    *b:ale_html_tidy_executable*
   Type: |String|