diff --git a/system/src/Grav/Common/Filesystem/RecursiveDirectoryFilterIterator.php b/system/src/Grav/Common/Filesystem/RecursiveDirectoryFilterIterator.php
index e41a32f5f..5422ffdd0 100644
--- a/system/src/Grav/Common/Filesystem/RecursiveDirectoryFilterIterator.php
+++ b/system/src/Grav/Common/Filesystem/RecursiveDirectoryFilterIterator.php
@@ -49,7 +49,7 @@ public function __construct(RecursiveIterator $iterator, $root, $ignore_folders,
      *
      * @return bool true if the current element is acceptable, otherwise false.
      */
-    public function accept()
+    public function accept() :bool
     {
         /** @var SplFileInfo $file */
         $file = $this->current();
@@ -72,7 +72,7 @@ public function accept()
     /**
      * @return RecursiveDirectoryFilterIterator|RecursiveFilterIterator
      */
-    public function getChildren()
+    public function getChildren() :RecursiveFilterIterator
     {
         /** @var RecursiveDirectoryFilterIterator $iterator */
         $iterator = $this->getInnerIterator();
diff --git a/system/src/Grav/Common/Filesystem/RecursiveFolderFilterIterator.php b/system/src/Grav/Common/Filesystem/RecursiveFolderFilterIterator.php
index 66d917212..d027b6b91 100644
--- a/system/src/Grav/Common/Filesystem/RecursiveFolderFilterIterator.php
+++ b/system/src/Grav/Common/Filesystem/RecursiveFolderFilterIterator.php
@@ -45,7 +45,7 @@ public function __construct(RecursiveIterator $iterator, $ignore_folders = [])
      *
      * @return bool true if the current element is acceptable, otherwise false.
      */
-    public function accept()
+    public function accept() :bool
     {
         /** @var SplFileInfo $current */
         $current = $this->current();