diff --git a/Api/CategoryUrlRetrieverInterface.php b/Api/CategoryUrlRetrieverInterface.php
new file mode 100644
index 0000000..d41d651
--- /dev/null
+++ b/Api/CategoryUrlRetrieverInterface.php
@@ -0,0 +1,6 @@
+<?php
+namespace Staempfli\Seo\Api;
+
+interface CategoryUrlRetrieverInterface extends UrlRetrieverInterface
+{
+}
\ No newline at end of file
diff --git a/Api/CmsPageUrlRetrieverInterface.php b/Api/CmsPageUrlRetrieverInterface.php
new file mode 100644
index 0000000..440ccee
--- /dev/null
+++ b/Api/CmsPageUrlRetrieverInterface.php
@@ -0,0 +1,6 @@
+<?php
+namespace Staempfli\Seo\Api;
+
+interface CmsPageUrlRetrieverInterface extends UrlRetrieverInterface
+{
+}
\ No newline at end of file
diff --git a/Api/ProductUrlRetrieverInterface.php b/Api/ProductUrlRetrieverInterface.php
new file mode 100644
index 0000000..75c028d
--- /dev/null
+++ b/Api/ProductUrlRetrieverInterface.php
@@ -0,0 +1,6 @@
+<?php
+namespace Staempfli\Seo\Api;
+
+interface ProductUrlRetrieverInterface extends UrlRetrieverInterface
+{
+}
\ No newline at end of file
diff --git a/Service/HrefLang/AlternativeUrlService.php b/Service/HrefLang/AlternativeUrlService.php
index 5a3fc38..30eeb0f 100644
--- a/Service/HrefLang/AlternativeUrlService.php
+++ b/Service/HrefLang/AlternativeUrlService.php
@@ -4,30 +4,33 @@
 
 use Magento\Framework\App\Request\Http as HttpRequest;
 use Magento\Store\Model\Store;
+use Staempfli\Seo\Api\CategoryUrlRetrieverInterface;
+use Staempfli\Seo\Api\CmsPageUrlRetrieverInterface;
+use Staempfli\Seo\Api\ProductUrlRetrieverInterface;
 
 class AlternativeUrlService
 {
     /**
-     * @var CmsPageUrlRetriever
+     * @var CmsPageUrlRetrieverInterface
      */
     private $cmsPageUrlRetriever;
     /**
-     * @var HttpRequest
-     */
-    private $request;
-    /**
-     * @var CategoryUrlRetriever
+     * @var CategoryUrlRetrieverInterface
      */
     private $categoryUrlRetriever;
     /**
-     * @var ProductUrlRetriever
+     * @var ProductUrlRetrieverInterface
      */
     private $productUrlRetriever;
+    /**
+     * @var HttpRequest
+     */
+    private $request;
 
     public function __construct(
-        CmsPageUrlRetriever $cmsPageUrlRetriever,
-        CategoryUrlRetriever $categoryUrlRetriever,
-        ProductUrlRetriever $productUrlRetriever,
+        CmsPageUrlRetrieverInterface $cmsPageUrlRetriever,
+        CategoryUrlRetrieverInterface $categoryUrlRetriever,
+        ProductUrlRetrieverInterface $productUrlRetriever,
         HttpRequest $request
     ) {
         $this->cmsPageUrlRetriever = $cmsPageUrlRetriever;
diff --git a/Service/HrefLang/CategoryUrlRetriever.php b/Service/HrefLang/CategoryUrlRetriever.php
index 6758a84..d45bc91 100644
--- a/Service/HrefLang/CategoryUrlRetriever.php
+++ b/Service/HrefLang/CategoryUrlRetriever.php
@@ -6,9 +6,9 @@
 use Magento\Catalog\Model\Category;
 use Magento\CatalogUrlRewrite\Model\CategoryUrlPathGenerator;
 use Magento\Store\Model\Store;
-use Staempfli\Seo\Api\UrlRetrieverInterface;
+use Staempfli\Seo\Api\CategoryUrlRetrieverInterface;
 
-class CategoryUrlRetriever implements UrlRetrieverInterface
+class CategoryUrlRetriever implements CategoryUrlRetrieverInterface
 {
     /**
      * @var CategoryRepositoryInterface
diff --git a/Service/HrefLang/CmsPageUrlRetriever.php b/Service/HrefLang/CmsPageUrlRetriever.php
index ac423b8..0ca9fc1 100644
--- a/Service/HrefLang/CmsPageUrlRetriever.php
+++ b/Service/HrefLang/CmsPageUrlRetriever.php
@@ -7,9 +7,9 @@
 use Magento\CmsUrlRewrite\Model\CmsPageUrlPathGenerator;
 use Magento\Framework\Exception\LocalizedException;
 use Magento\Store\Model\Store;
-use Staempfli\Seo\Api\UrlRetrieverInterface;
+use Staempfli\Seo\Api\CmsPageUrlRetrieverInterface;
 
-class CmsPageUrlRetriever implements UrlRetrieverInterface
+class CmsPageUrlRetriever implements CmsPageUrlRetrieverInterface
 {
     /**
      * @var PageRepositoryInterface
diff --git a/Service/HrefLang/ProductUrlRetriever.php b/Service/HrefLang/ProductUrlRetriever.php
index f5c6898..f41399e 100644
--- a/Service/HrefLang/ProductUrlRetriever.php
+++ b/Service/HrefLang/ProductUrlRetriever.php
@@ -6,9 +6,9 @@
 use Magento\Catalog\Model\Product;
 use Magento\CatalogUrlRewrite\Model\ProductUrlPathGenerator;
 use Magento\Store\Model\Store;
-use Staempfli\Seo\Api\UrlRetrieverInterface;
+use Staempfli\Seo\Api\ProductUrlRetrieverInterface;
 
-class ProductUrlRetriever implements UrlRetrieverInterface
+class ProductUrlRetriever implements ProductUrlRetrieverInterface
 {
     /**
      * @var ProductRepositoryInterface
diff --git a/etc/frontend/di.xml b/etc/frontend/di.xml
index ed2e5f5..12edb0f 100644
--- a/etc/frontend/di.xml
+++ b/etc/frontend/di.xml
@@ -6,6 +6,9 @@
  */
 -->
 <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
+    <preference for="Staempfli\Seo\Api\CmsPageUrlRetrieverInterface" type="Staempfli\Seo\Service\HrefLang\CmsPageUrlRetriever" />
+    <preference for="Staempfli\Seo\Api\CategoryUrlRetrieverInterface" type="Staempfli\Seo\Service\HrefLang\CategoryUrlRetriever" />
+    <preference for="Staempfli\Seo\Api\ProductUrlRetrieverInterface" type="Staempfli\Seo\Service\HrefLang\ProductUrlRetriever" />
     <type name="Magento\Framework\View\Page\Config">
         <plugin name="staempfli_seo" type="Staempfli\Seo\Plugin\PageConfigPlugin" />
     </type>