diff --git a/Input/Input.php b/Input/Input.php
index 8c7905db7..ff5d3170f 100644
--- a/Input/Input.php
+++ b/Input/Input.php
@@ -104,7 +104,7 @@ public function getArguments()
     /**
      * {@inheritdoc}
      */
-    public function getArgument($name)
+    public function getArgument(string $name)
     {
         if (!$this->definition->hasArgument($name)) {
             throw new InvalidArgumentException(sprintf('The "%s" argument does not exist.', $name));
@@ -116,7 +116,7 @@ public function getArgument($name)
     /**
      * {@inheritdoc}
      */
-    public function setArgument($name, $value)
+    public function setArgument(string $name, $value)
     {
         if (!$this->definition->hasArgument($name)) {
             throw new InvalidArgumentException(sprintf('The "%s" argument does not exist.', $name));