diff --git a/src/JsonFeedV1Serializer.php b/src/JsonFeedV1Serializer.php
index 746c395..f48072e 100644
--- a/src/JsonFeedV1Serializer.php
+++ b/src/JsonFeedV1Serializer.php
@@ -17,7 +17,7 @@ class JsonFeedV1Serializer extends ArraySerializer
     /**
      * @inheritdoc
      */
-    public function collection($resourceKey, array $data)
+    public function collection($resourceKey, array $data): array
     {
         return ['items' => $data];
     }
@@ -25,7 +25,7 @@ public function collection($resourceKey, array $data)
     /**
      * @inheritdoc
      */
-    public function meta(array $meta)
+    public function meta(array $meta): array
     {
         return array_merge([
             'version' => 'https://jsonfeed.org/version/1.1',
@@ -38,7 +38,7 @@ public function meta(array $meta)
     /**
      * @inheritdoc
      */
-    public function paginator(PaginatorInterface $paginator)
+    public function paginator(PaginatorInterface $paginator): array
     {
         $currentPage = (int)$paginator->getCurrentPage();
         $lastPage = (int)$paginator->getLastPage();
diff --git a/src/PaginatorAdapter.php b/src/PaginatorAdapter.php
index 3533250..236a7b4 100644
--- a/src/PaginatorAdapter.php
+++ b/src/PaginatorAdapter.php
@@ -65,7 +65,7 @@ public function __construct($elementsPerPage, $totalElements, $pageParam)
      *
      * @return int
      */
-    public function getCurrentPage()
+    public function getCurrentPage(): int
     {
         return $this->currentPage;
     }
@@ -75,7 +75,7 @@ public function getCurrentPage()
      *
      * @return int
      */
-    public function getLastPage()
+    public function getLastPage(): int
     {
         return $this->totalPages;
     }
@@ -85,7 +85,7 @@ public function getLastPage()
      *
      * @return int
      */
-    public function getTotal()
+    public function getTotal(): int
     {
         return $this->totalElements;
     }
@@ -95,7 +95,7 @@ public function getTotal()
      *
      * @return int
      */
-    public function getCount()
+    public function getCount(): int
     {
         return $this->count;
     }
@@ -115,7 +115,7 @@ public function setCount($count)
      *
      * @return int
      */
-    public function getPerPage()
+    public function getPerPage(): int
     {
         return $this->elementsPerPage;
     }
@@ -126,7 +126,7 @@ public function getPerPage()
      * @param int $page
      * @return string
      */
-    public function getUrl($page)
+    public function getUrl($page): string
     {
         $request = Craft::$app->getRequest();