diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 4eb4aa7c..ec8b501b 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -24,6 +24,10 @@ jobs:
           - "27.1"
           - snapshot
         include:
+          - emacs_version: "24.4"
+            allow_failure: true
+          - emacs_version: "24.5"
+            allow_failure: true
           - emacs_version: snapshot
             allow_failure: true
     steps:
diff --git a/lisp/php-mode.el b/lisp/php-mode.el
index 4488561f..cfedd586 100644
--- a/lisp/php-mode.el
+++ b/lisp/php-mode.el
@@ -480,7 +480,7 @@ In that case set to `NIL'."
 (c-lang-defconst c-class-decl-kwds
   "Keywords introducing declarations where the following block (if any)
 contains another declaration level that should be considered a class."
-  php '("class" "trait" "interface"))
+  php '("class" "trait" "interface" "enum"))
 
 (c-lang-defconst c-brace-list-decl-kwds
   "Keywords introducing declarations where the following block (if
@@ -493,7 +493,7 @@ PHP does not have an \"enum\"-like keyword."
   php (append (c-lang-const c-class-decl-kwds) '("function")))
 
 (c-lang-defconst c-modifier-kwds
-  php '("abstract" "const" "final" "static"))
+  php '("abstract" "const" "final" "static" "case"))
 
 (c-lang-defconst c-protection-kwds
   "Access protection label keywords in classes."
diff --git a/tests/8.1/enum.php b/tests/8.1/enum.php
new file mode 100644
index 00000000..a8525cd8
--- /dev/null
+++ b/tests/8.1/enum.php
@@ -0,0 +1,17 @@
+<?php
+
+enum Size
+{
+    case Small;
+    case Medium;
+    case Large;
+
+    public static function fromLength(int $cm)
+    {
+        return match(true) {
+            $cm < 50 => static::Small,
+            $cm < 100 => static::Medium,
+            default => static::Large,
+        };
+    }
+}
diff --git a/tests/8.1/enum.php.faces b/tests/8.1/enum.php.faces
new file mode 100644
index 00000000..2a1b66f5
--- /dev/null
+++ b/tests/8.1/enum.php.faces
@@ -0,0 +1,85 @@
+;; -*- mode: emacs-lisp -*-
+(("<?php" . php-php-tag)
+ ("
+
+")
+ ("enum" . php-keyword)
+ (" ")
+ ("Size" . font-lock-type-face)
+ ("
+{
+    ")
+ ("case" . php-keyword)
+ (" ")
+ ("Small" . font-lock-type-face)
+ (";
+    ")
+ ("case" . php-keyword)
+ (" ")
+ ("Medium" . font-lock-type-face)
+ (";
+    ")
+ ("case" . php-keyword)
+ (" ")
+ ("Large" . font-lock-type-face)
+ (";
+
+    ")
+ ("public" . php-keyword)
+ (" ")
+ ("static" . php-keyword)
+ (" ")
+ ("function" . php-keyword)
+ (" ")
+ ("fromLength" . php-function-name)
+ ("(")
+ ("int" . font-lock-type-face)
+ (" ")
+ ("$" . php-variable-sigil)
+ ("cm" . php-variable-name)
+ (")
+    {
+        ")
+ ("return" . php-keyword)
+ (" ")
+ ("match" . php-keyword)
+ ("(")
+ ("true" . php-constant)
+ (") {
+            ")
+ ("$" . php-variable-sigil)
+ ("cm" . php-variable-name)
+ (" ")
+ ("<" . php-comparison-op)
+ (" 50 ")
+ ("=" . php-assignment-op)
+ (">" . php-comparison-op)
+ (" ")
+ ("static" . php-keyword)
+ ("::" . php-paamayim-nekudotayim)
+ ("Small,
+            ")
+ ("$" . php-variable-sigil)
+ ("cm" . php-variable-name)
+ (" ")
+ ("<" . php-comparison-op)
+ (" 100 ")
+ ("=" . php-assignment-op)
+ (">" . php-comparison-op)
+ (" ")
+ ("static" . php-keyword)
+ ("::" . php-paamayim-nekudotayim)
+ ("Medium,
+            ")
+ ("default" . php-keyword)
+ (" ")
+ ("=" . php-assignment-op)
+ (">" . php-comparison-op)
+ (" ")
+ ("static" . php-keyword)
+ ("::" . php-paamayim-nekudotayim)
+ ("Large,
+        };
+    }
+}
+"))
\ No newline at end of file
diff --git a/tests/php-mode-test.el b/tests/php-mode-test.el
index 670304a9..b01b60aa 100644
--- a/tests/php-mode-test.el
+++ b/tests/php-mode-test.el
@@ -654,6 +654,10 @@ Meant for `php-mode-test-issue-503'."
   (with-php-mode-test ("7.4/arrow-function.php" :faces t))
   (with-php-mode-test ("7.4/typed-property.php" :faces t)))
 
+(ert-deftest php-mode-test-php81 ()
+  "Test highlighting language constructs added in PHP 8.1."
+  (with-php-mode-test ("8.1/enum.php" :faces t)))
+
 (ert-deftest php-mode-test-lang ()
   "Test highlighting for language constructs."
   (with-php-mode-test ("lang/class/anonymous-class.php" :indent t :magic t :faces t))