diff --git a/src/Type/Definition/FieldDefinition.php b/src/Type/Definition/FieldDefinition.php
index 19199c3..a98dcd5 100644
--- a/src/Type/Definition/FieldDefinition.php
+++ b/src/Type/Definition/FieldDefinition.php
@@ -62,6 +62,11 @@ class FieldDefinition
      */
     public $config;
 
+    /**
+     * @var null|callable
+     */
+    public $complexityFn;
+
     /**
      * @var OutputType
      */
@@ -108,7 +113,7 @@ class FieldDefinition
     }
 
     /**
-     * @param array|Config $field
+     * @param array $field
      * @param string $typeName
      * @return FieldDefinition
      */