diff --git a/README.ja.md b/README.ja.md
index 7dd7c87c..b7530b95 100644
--- a/README.ja.md
+++ b/README.ja.md
@@ -294,14 +294,6 @@ PHPモードはデフォルトでは`php-enable-default-coding-style`関数で
このスタイルはSymfony2のコードベースで広く利用されていますが、慣習についての文書で明示的に言及されているものではありません。
-### 定数の追加
-
-フレームワークによって一般的な定数群が定義されるならば、変数`php-extra-constants`を値をカスタマイズすることができます。これはPHPモードが追加の定数として扱う定数名の文字列のリストです。これらの定数はPHP組み込みの定数と同じ強調表示を行います。
-
-### Web Mode定数とキーワード
-
-もしあなたが[Web Mode]を使用しているなら、Web Modeに設定された追加のPHP定数をとキーワードを追加しようとします。
-
### HTMLテンプレートのサポートを無効化する
多くの開発者はPHPモードで純粋なPHPスクリプト(HTMLテンプレートを含まないもの)を編集します。HTMLとの互換レイヤーはPHPモードの歴史的な機能ですが、完全には機能していません。速度の低下や強調表示を破壊するおそれがあるなどの副作用があります。変数`php-template-compatibility`を`nil`にセットすると、HTMLとの互換性を無効化することができます。HTMLやその他のマークアップ言語のテンプレートエンジンを含むPHPスクリプトを開発する際は[Web Mode][]は優れた選択肢です。
diff --git a/README.md b/README.md
index 2bd062f3..6e9801ce 100644
--- a/README.md
+++ b/README.md
@@ -271,14 +271,6 @@ With this style method call chains can be formatted with indented continuation a
This style is used widely throughout Symfony2 source code even if it is not explicitly mentioned in their conventions documents.
-### Extra Constants
-
-If you commonly use a framework or library that defines a set of constants then you may wish to customize the value of `php-extra-constants`. It is a list of strings that PHP Mode will treat as additional constants, i.e. providing them the same level syntax highlighting that PHP Mode uses for built-in constants.
-
-### Web Mode Constants and Keywords
-
-If you use [Web Mode][] then PHP Mode will attempt to use any additional PHP constants and keywords that Web Mode allows you to define.
-
### Avoid HTML Template Compatibility
Many developers use PHP Mode to edit pure PHP scripts (e.g. files with only PHP and no HTML). A basic compatibility layer with HTML has historically been part of PHP Mode but it does not work perfectly and can cause some bad side effects such as slowness and incorrect font locking. Configuring the `php-template-compatibility` property with a `nil` will cancel any attempt of HTML compatibility. [Web Mode](http://web-mode.org/) is a great alternative to PHP Mode if you need to work with PHP scripts that do contain HTML and other markup.
diff --git a/php-mode.el b/php-mode.el
index f8c93295..3750b9e2 100644
--- a/php-mode.el
+++ b/php-mode.el
@@ -160,30 +160,6 @@ Turning this on will open it whenever `php-mode' is loaded."
:tag "PHP Mode Template Compatibility"
:type 'boolean)
-(defun php-mode-extra-constants-create-regexp (kwds)
- "Create regexp for the list of extra constant keywords KWDS."
- (concat "[^_$]?\\<\\("
- (regexp-opt
- (append kwds
- (when (boundp 'web-mode-extra-php-constants) web-mode-extra-php-constants)))
- "\\)\\>[^_]?"))
-
-(defun php-mode-extra-constants-set (sym value)
- "Apply the list of extra constant keywords `VALUE'.
-
-This function is called when the custom variable php-extra-constants
-is updated. The web-mode-extra-constants list is appended to the list
-of constants when set."
- ;; remove old keywords
- (when (boundp 'php-extra-constants)
- (font-lock-remove-keywords
- 'php-mode `((,(php-mode-extra-constants-create-regexp php-extra-constants) 1 'php-constant))))
- ;; add new keywords
- (when value
- (font-lock-add-keywords
- 'php-mode `((,(php-mode-extra-constants-create-regexp value) 1 'php-constant))))
- (set sym value))
-
(define-obsolete-variable-alias 'php-lineup-cascaded-calls 'php-mode-lineup-cascaded-calls "1.20.0")
(defcustom php-mode-lineup-cascaded-calls nil
"Indent chained method calls to the previous line."
@@ -201,14 +177,6 @@ of constants when set."
:tag "PHP Mode Page Delimiter"
:type 'regexp)
-(define-obsolete-variable-alias 'php-extra-constants 'php-mode-extra-constants "1.20.0")
-(defcustom php-mode-extra-constants '()
- "A list of additional strings to treat as PHP constants."
- :group 'php-mode
- :tag "PHP Mode Extra Constants"
- :type '(repeat string)
- :set 'php-mode-extra-constants-set)
-
(define-obsolete-variable-alias 'php-do-not-use-semantic-imenu 'php-mode-do-not-use-semantic-imenu "1.20.0")
(defcustom php-mode-do-not-use-semantic-imenu t
"Customize `imenu-create-index-function' for `php-mode'.
diff --git a/tests/constants.php b/tests/constants.php
index 037638ce..26868301 100644
--- a/tests/constants.php
+++ b/tests/constants.php
@@ -12,9 +12,6 @@
no_constant;
no_CONSTANT;
-// Test php-extra-constants
-extraconstant;
-
// Everything called statically should be highlighted with the constant face
// (like c++-mode)
ClassName::$test;
diff --git a/tests/constants.php.faces b/tests/constants.php.faces
index 6a2801ce..28f9523d 100644
--- a/tests/constants.php.faces
+++ b/tests/constants.php.faces
@@ -30,9 +30,6 @@
("IS_CONSTANT99" . php-constant)
(";\nno_constant;\nno_CONSTANT;\n\n")
("// " . font-lock-comment-delimiter-face)
- ("Test php-extra-constants\n" . font-lock-comment-face)
- ("extraconstant;\n\n")
- ("// " . font-lock-comment-delimiter-face)
("Everything called statically should be highlighted with the constant face\n" . font-lock-comment-face)
("// " . font-lock-comment-delimiter-face)
("(like c++-mode)\n" . font-lock-comment-face)
diff --git a/tests/php-mode-test.el b/tests/php-mode-test.el
index f83e7fa7..d41217cd 100644
--- a/tests/php-mode-test.el
+++ b/tests/php-mode-test.el
@@ -370,25 +370,6 @@ style from Drupal."
(ert-deftest php-mode-test-constants ()
"Proper highlighting for constants."
- (custom-set-variables '(php-extra-constants (quote ("extraconstant"))))
- (with-php-mode-test ("constants.php")
- (let ((variables '(
- "true" "TRUE"
- "false" "FALSE"
- "null" "NULL"
- "IS_CONSTANT"
- "__IS_CONSTANT__"
- "IS_CONSTANT99"
- "extraconstant"
- "ClassName")))
- (dolist (variable variables)
- (search-forward variable)
- (goto-char (match-beginning 0))
- (should (equal (cons variable 'php-constant)
- (cons variable (get-text-property (point) 'face)))))))
-
- ;; Set default
- (custom-set-variables '(php-extra-constants (quote ())))
(with-php-mode-test ("constants.php" :faces t)))
(ert-deftest php-mode-test-identifiers()