diff --git a/src/Contracts/Data.php b/src/Contracts/Data.php
index 5ed52a79..e0e42ce3 100644
--- a/src/Contracts/Data.php
+++ b/src/Contracts/Data.php
@@ -29,7 +29,7 @@ public function offsetUnset($offset): void
     }
 
     #[\ReturnTypeWillChange]
-    public function offsetGet($offset)
+    public function offsetGet($offset): mixed
     {
         if (isset($this->data[$offset])) {
             return $this->data[$offset];