diff --git a/composer.json b/composer.json
index 5a8c847..c1f80d8 100644
--- a/composer.json
+++ b/composer.json
@@ -24,6 +24,33 @@
         "bin/mdphpcs"
     ],
     "require-dev": {
-        "phpunit/phpunit": "^9.6"
+        "phpunit/phpunit": "^9.6",
+        "mikey179/vfsstream": "^1.6.10"
+    },
+    "prefer-stable": true,
+    "minimum-stability": "dev",
+    "config": {
+        "preferred-install": {
+            "silverstripe/*": "source",
+            "creative-commoners/*": "source",
+            "symbiote/*": "source",
+            "dnadesign/*": "source",
+            "bringyourownideas/*": "source",
+            "colymba/*": "source",
+            "cwp/*": "source",
+            "tractorcow/*": "source",
+            "*": "dist"
+        },
+        "platform": {
+            "php": "8.1"
+        },
+        "allow-plugins": {
+            "composer/installers": true,
+            "silverstripe/recipe-plugin": true,
+            "silverstripe/vendor-plugin": true
+        }
+    },
+    "conflict": {
+        "silverstripe/vendor-plugin": "<1.5.2"
     }
 }
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 4318681..b5872d9 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,6 +1,9 @@
 <?php
 
 // php_codesniffer autoloader
+
+use PHP_CodeSniffer\Util\Tokens;
+
 $autoloadCandidates = [
     // running from package itself as root
     __DIR__ . '/../vendor/squizlabs/php_codesniffer/autoload.php',
@@ -21,6 +24,9 @@
     throw new RuntimeException("Couldn't find autoloader");
 }
 
+// Required to correctly run constant definitions in CI, though not needed locally for some reason.
+Tokens::$operators;
+
 if (!defined('PHP_CODESNIFFER_VERBOSITY')) {
     define('PHP_CODESNIFFER_VERBOSITY', 0);
 }