diff --git a/deprecated.js b/deprecated.js
new file mode 100644
index 0000000000..18b11cc369
--- /dev/null
+++ b/deprecated.js
@@ -0,0 +1,26 @@
+Reset = "\x1b[0m"
+FgRed = "\x1b[31m"
+FgWhite = "\x1b[37m"
+FgWhite = "\x1b[37m"
+Bright = "\x1b[1m"
+FgBlue = "\x1b[34m"
+BgRed = "\x1b[41m"
+
+DEPRECATION = `
+${BgRed + FgWhite}
+-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
+${Reset}${Bright}${FgWhite}
+ Verion 9 of Highlight.js has reached EOL.  It will no longer
+ be supported or receive security updates in the future.
+ Please upgrade to version 10.
+
+ For more info:
+ ${FgBlue}
+ https://github.com/highlightjs/highlight.js/issues/2877
+ https://github.com/highlightjs/highlight.js/blob/master/VERSION_10_UPGRADE.md
+ ${BgRed + FgWhite}
+ -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
+${Reset}
+`.trim()
+
+console.log(DEPRECATION)
diff --git a/docs/conf.py b/docs/conf.py
index 2411239996..c5558a7c27 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -50,7 +50,7 @@
 # The short X.Y version.
 version = '9.18'
 # The full version, including alpha/beta/rc tags.
-release = '9.18.3'
+release = '9.18.4'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/package-lock.json b/package-lock.json
index 5ac08311e5..15b2cf1a1c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "highlight.js",
-  "version": "9.18.3",
+  "version": "9.18.4",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index f93d1fee50..31b8b4ced3 100644
--- a/package.json
+++ b/package.json
@@ -6,7 +6,7 @@
     "syntax"
   ],
   "homepage": "https://highlightjs.org/",
-  "version": "9.18.3",
+  "version": "9.18.4",
   "author": {
     "name": "Ivan Sagalaev",
     "email": "maniac@softwaremaniacs.org"
@@ -24,6 +24,7 @@
   "scripts": {
     "mocha": "mocha",
     "test": "mocha --globals document test",
+    "postinstall": "node deprecated.js",
     "test-browser": "mocha --globals document test/browser"
   },
   "engines": {
diff --git a/tools/build.js b/tools/build.js
index d39955139b..333b9fbdfa 100644
--- a/tools/build.js
+++ b/tools/build.js
@@ -64,6 +64,7 @@ let commander = require('commander');
 let path      = require('path');
 let Queue     = require('gear').Queue;
 let registry  = require('./tasks');
+let fs = require('fs');
 
 let build, dir = {};
 
@@ -85,5 +86,7 @@ new Queue({ registry: registry })
   .clean(dir.build)
   .log('Starting build.')
   .series(build(commander, dir))
+  .read(["deprecated.js"])
+  .dest("./build")
   .log('Finished build.')
-  .run();
+  .run()