diff --git a/composer.json b/composer.json
index f18dac2f6e..aba213db28 100644
--- a/composer.json
+++ b/composer.json
@@ -4,7 +4,7 @@
   "type": "project",
   "license": "MIT",
   "require-dev": {
-    "phpunit/phpunit": "^11.0"
+    "phpunit/phpunit": "^13.3"
   },
   "config": {
     "sort-packages": true
diff --git a/utils/install/php.py b/utils/install/php.py
index 3bb2414f29..f46a1df4b2 100644
--- a/utils/install/php.py
+++ b/utils/install/php.py
@@ -19,7 +19,7 @@ _PHPUNIT_EXTENSIONS = ("dom", "mbstring", "xmlwriter")
 def ensure_php_toolchain() -> None:
     """Install the PHP interpreter, Composer and the extensions PHPUnit needs.
 
-    ``phpunit/phpunit ^11`` declares ``_PHPUNIT_EXTENSIONS`` as platform
+    ``phpunit/phpunit ^13`` declares ``_PHPUNIT_EXTENSIONS`` as platform
     requirements and Composer refuses to resolve the vendor tree without them,
     so they are part of the toolchain rather than of the suite consuming it.
     A distro ships them as packages separate from the interpreter, which is why