diff --git a/src/Model/SitemapUrl.php b/src/Model/SitemapUrl.php
index ae88ffb9..7897cb00 100644
--- a/src/Model/SitemapUrl.php
+++ b/src/Model/SitemapUrl.php
@@ -38,7 +38,7 @@ class SitemapUrl implements SitemapUrlInterface
     /**
      * {@inheritdoc}
      */
-    public function addAlternative($location, $locale): void
+    public function addAlternative(string $location, string $locale): void
     {
         $this->alternatives[$locale] = $location;
     }
@@ -46,7 +46,7 @@ public function addAlternative($location, $locale): void
     /**
      * {@inheritdoc}
      */
-    public function setAlternatives(array $alternatives): void
+    public function setAlternatives(iterable $alternatives): void
     {
         $this->alternatives = $alternatives;
     }
diff --git a/src/Model/SitemapUrlInterface.php b/src/Model/SitemapUrlInterface.php
index 14e28dd5..6c22d539 100644
--- a/src/Model/SitemapUrlInterface.php
+++ b/src/Model/SitemapUrlInterface.php
@@ -21,17 +21,18 @@ public function getLocalization(): ?string;
     public function setLocalization(string $localization): void;
 
     /**
-     * {@inheritdoc}
+     * @param string $location
+     * @param string $locale
      */
-    public function addAlternative($location, $locale): void;
+    public function addAlternative(string $location, string $locale): void;
 
     /**
-     * {@inheritdoc}
+     * @param iterable $alternatives
      */
-    public function setAlternatives(array $alternatives): void;
+    public function setAlternatives(iterable $alternatives): void;
 
     /**
-     * {@inheritdoc}
+     * @return iterable
      */
     public function getAlternatives(): iterable;
 
@@ -46,7 +47,7 @@ public function getLastModification(): ?DateTimeInterface;
     public function setLastModification(DateTimeInterface $lastModification): void;
 
     /**
-     * @return ChangeFrequency
+     * @return string
      */
     public function getChangeFrequency(): string;