diff --git a/src/Symfony/Component/DomCrawler/AbstractUriElement.php b/src/Symfony/Component/DomCrawler/AbstractUriElement.php
index 83b2433c8f..6db5b74039 100644
--- a/src/Symfony/Component/DomCrawler/AbstractUriElement.php
+++ b/src/Symfony/Component/DomCrawler/AbstractUriElement.php
@@ -35,7 +35,7 @@ abstract class AbstractUriElement
 
     /**
      * @param \DOMElement $node       A \DOMElement instance
-     * @param string      $currentUri The URI of the page where the link is embedded (or the base href)
+     * @param string|null $currentUri The URI of the page where the link is embedded (or the base href)
      * @param string|null $method     The method to use for the link (GET by default)
      *
      * @throws \InvalidArgumentException if the node is not a link
diff --git a/src/Symfony/Component/DomCrawler/Crawler.php b/src/Symfony/Component/DomCrawler/Crawler.php
index 8f12764474..f8839e875b 100644
--- a/src/Symfony/Component/DomCrawler/Crawler.php
+++ b/src/Symfony/Component/DomCrawler/Crawler.php
@@ -21,20 +21,29 @@ use Symfony\Component\CssSelector\CssSelectorConverter;
  */
 class Crawler implements \Countable, \IteratorAggregate
 {
+    /**
+     * @var string|null
+     */
     protected $uri;
 
     /**
-     * @var string The default namespace prefix to be used with XPath and CSS expressions
+     * The default namespace prefix to be used with XPath and CSS expressions.
+     *
+     * @var string
      */
     private $defaultNamespacePrefix = 'default';
 
     /**
-     * @var array A map of manually registered namespaces
+     * A map of manually registered namespaces.
+     *
+     * @var array<string, string>
      */
     private $namespaces = [];
 
     /**
-     * @var string The base href value
+     * The base href value.
+     *
+     * @var string|null
      */
     private $baseHref;
 
@@ -75,7 +84,7 @@ class Crawler implements \Countable, \IteratorAggregate
     /**
      * Returns the current URI.
      *
-     * @return string
+     * @return string|null
      */
     public function getUri()
     {
@@ -85,7 +94,7 @@ class Crawler implements \Countable, \IteratorAggregate
     /**
      * Returns base href.
      *
-     * @return string
+     * @return string|null
      */
     public function getBaseHref()
     {
diff --git a/src/Symfony/Component/DomCrawler/Form.php b/src/Symfony/Component/DomCrawler/Form.php
index f3cee8669a..02f9869122 100644
--- a/src/Symfony/Component/DomCrawler/Form.php
+++ b/src/Symfony/Component/DomCrawler/Form.php
@@ -38,9 +38,9 @@ class Form extends Link implements \ArrayAccess
 
     /**
      * @param \DOMElement $node       A \DOMElement instance
-     * @param string      $currentUri The URI of the page where the form is embedded
-     * @param string      $method     The method to use for the link (if null, it defaults to the method defined by the form)
-     * @param string      $baseHref   The URI of the <base> used for relative links, but not for empty action
+     * @param string|null $currentUri The URI of the page where the form is embedded
+     * @param string|null $method     The method to use for the link (if null, it defaults to the method defined by the form)
+     * @param string|null $baseHref   The URI of the <base> used for relative links, but not for empty action
      *
      * @throws \LogicException if the node is not a button inside a form tag
      */