diff --git a/src/Result/AbstractListResult.php b/src/Result/AbstractListResult.php
index 42e4d5c..0ad83b0 100644
--- a/src/Result/AbstractListResult.php
+++ b/src/Result/AbstractListResult.php
@@ -6,7 +6,7 @@
 
 abstract class AbstractListResult extends AbstractResult implements \Countable
 {
-    public function count()
+    public function count(): int
     {
         return count($this->getData());
     }