diff --git a/system/src/Grav/Framework/Collection/AbstractLazyCollection.php b/system/src/Grav/Framework/Collection/AbstractLazyCollection.php
index 806939cf52..6d98bc8895 100644
--- a/system/src/Grav/Framework/Collection/AbstractLazyCollection.php
+++ b/system/src/Grav/Framework/Collection/AbstractLazyCollection.php
@@ -26,7 +26,7 @@ abstract class AbstractLazyCollection extends BaseAbstractLazyCollection impleme
      * @par ArrayCollection
      * @phpstan-var ArrayCollection<TKey,T>
      */
-    protected $collection;
+    protected ?\Doctrine\Common\Collections\Collection $collection;
 
     /**
      * {@inheritDoc}