diff --git a/src/Utils/CombinationsArrayIterator.php b/src/Utils/CombinationsArrayIterator.php
index 1cf2806..110f9c4 100644
--- a/src/Utils/CombinationsArrayIterator.php
+++ b/src/Utils/CombinationsArrayIterator.php
@@ -32,29 +32,26 @@ class CombinationsArrayIterator implements Iterator
         $this->rewind();
     }
 
-    #[\ReturnTypeWillChange]
-    public function rewind()
+    public function rewind(): void
     {
         if (!$this->numArrays) {
             $this->isValid = false;
         } else {
             $this->isValid = true;
             $this->k = 0;
-            
+
             for ($i = 0; $i < $this->numArrays; $i++) {
                 reset($this->arrays[$i]);
             }
         }
     }
 
-    #[\ReturnTypeWillChange]
-    public function valid()
+    public function valid(): bool
     {
         return $this->isValid;
     }
 
-    #[\ReturnTypeWillChange]
-    public function next()
+    public function next(): void
     {
         $this->k++;
 
@@ -71,8 +68,7 @@ class CombinationsArrayIterator implements Iterator
         }
     }
 
-    #[\ReturnTypeWillChange]
-    public function current()
+    public function current(): mixed
     {
         $res = array();
         for ($i = 0; $i < $this->numArrays; $i++) {
@@ -81,8 +77,7 @@ class CombinationsArrayIterator implements Iterator
         return $res;
     }
 
-    #[\ReturnTypeWillChange]
-    public function key()
+    public function key(): mixed
     {
         return $this->k;
     }
diff --git a/src/Utils/MultipleArrayIterator.php b/src/Utils/MultipleArrayIterator.php
index 1d94ee0..f1bba51 100644
--- a/src/Utils/MultipleArrayIterator.php
+++ b/src/Utils/MultipleArrayIterator.php
@@ -22,8 +22,7 @@ class MultipleArrayIterator implements Iterator
         $this->rewind();
     }
 
-    #[\ReturnTypeWillChange]
-    public function rewind()
+    public function rewind(): void
     {
         $this->active = $this->arrays;
         if ($this->active) {
@@ -31,20 +30,17 @@ class MultipleArrayIterator implements Iterator
         }
     }
 
-    #[\ReturnTypeWillChange]
-    public function current()
+    public function current(): mixed
     {
         return $this->active ? current($this->active[0]) : false;
     }
 
-    #[\ReturnTypeWillChange]
-    public function key()
+    public function key(): mixed
     {
         return $this->active ? key($this->active[0]) : false;
     }
 
-    #[\ReturnTypeWillChange]
-    public function next()
+    public function next(): void
     {
         if (!$this->active) {
             return;
@@ -58,8 +54,7 @@ class MultipleArrayIterator implements Iterator
         }
     }
 
-    #[\ReturnTypeWillChange]
-    public function valid()
+    public function valid(): bool
     {
         return $this->active && (current($this->active[0] ?? []) !== false);
     }