diff --git a/src/Type/Definition/Directive.php b/src/Type/Definition/Directive.php
index f2c546f93..31bb127d3 100644
--- a/src/Type/Definition/Directive.php
+++ b/src/Type/Definition/Directive.php
@@ -31,9 +31,9 @@ class Directive
     /**
      * Lazily initialized.
      *
-     * @var array<string, Directive>
+     * @var null|array<string, Directive>
      */
-    protected static array $internalDirectives = [];
+    protected static ?array $internalDirectives = null;
 
     public string $name;
 
@@ -90,11 +90,7 @@ public static function includeDirective(): Directive
      */
     public static function getInternalDirectives(): array
     {
-        if (self::$internalDirectives !== []) {
-            return self::$internalDirectives;
-        }
-
-        return self::$internalDirectives = [
+        return self::$internalDirectives ??= [
             'include' => new self([
                 'name' => self::INCLUDE_NAME,
                 'description' => 'Directs the executor to include this field or fragment only when the `if` argument is true.',
@@ -169,6 +165,6 @@ public static function isSpecifiedDirective(Directive $directive): bool
 
     public static function reset(): void
     {
-        self::$internalDirectives = [];
+        self::$internalDirectives = null;
     }
 }
diff --git a/src/Type/Definition/Type.php b/src/Type/Definition/Type.php
index 6a2a29c52..fc4262eff 100644
--- a/src/Type/Definition/Type.php
+++ b/src/Type/Definition/Type.php
@@ -31,10 +31,10 @@ abstract class Type implements \JsonSerializable
     ];
 
     /** @var array<string, ScalarType> */
-    protected static array $standardTypes = [];
+    protected static ?array $standardTypes = [];
 
-    /** @var array<string, Type&NamedType> */
-    protected static array $builtInTypes = [];
+    /** @var null|array<string, Type&NamedType> */
+    protected static ?array $builtInTypes = null;
 
     /**
      * @api
@@ -119,11 +119,7 @@ public static function nonNull($type): NonNull
      */
     public static function builtInTypes(): array
     {
-        if (self::$builtInTypes !== []) {
-            return self::$builtInTypes;
-        }
-
-        return self::$builtInTypes = \array_merge(
+        return self::$builtInTypes ??= \array_merge(
             Introspection::getTypes(),
             self::getStandardTypes()
         );
@@ -270,6 +266,6 @@ public function jsonSerialize(): string
     public static function reset(): void
     {
         static::$standardTypes = [];
-        static::$builtInTypes = [];
+        static::$builtInTypes = null;
     }
 }