diff --git a/config/phpstan-baseline.neon b/config/phpstan-baseline.neon
index 89348ca3..a9dcb0ba 100644
--- a/config/phpstan-baseline.neon
+++ b/config/phpstan-baseline.neon
@@ -43,8 +43,8 @@ parameters:
 			path: ../src/CSSList/Document.php
 
 		-
-			message: '#^Cannot call method render\(\) on string\.$#'
-			identifier: method.nonObject
+			message: '#^Method Sabberworm\\CSS\\Property\\CSSNamespace\:\:atRuleArgs\(\) should return array\<int, string\> but returns list\<Sabberworm\\CSS\\Value\\CSSString\|Sabberworm\\CSS\\Value\\URL\|string\>\.$#'
+			identifier: return.type
 			count: 1
 			path: ../src/Property/CSSNamespace.php
 
diff --git a/src/Property/CSSNamespace.php b/src/Property/CSSNamespace.php
index 78989d8a..155387ca 100644
--- a/src/Property/CSSNamespace.php
+++ b/src/Property/CSSNamespace.php
@@ -6,6 +6,8 @@
 
 use Sabberworm\CSS\Comment\Comment;
 use Sabberworm\CSS\OutputFormat;
+use Sabberworm\CSS\Value\CSSString;
+use Sabberworm\CSS\Value\URL;
 
 /**
  * `CSSNamespace` represents an `@namespace` rule.
@@ -13,7 +15,7 @@
 class CSSNamespace implements AtRule
 {
     /**
-     * @var string
+     * @var CSSString|URL
      */
     private $url;
 
@@ -35,11 +37,10 @@ class CSSNamespace implements AtRule
     protected $comments = [];
 
     /**
-     * @param string $url
-     * @param string|null $prefix
+     * @param CSSString|URL $url
      * @param int<0, max> $lineNumber
      */
-    public function __construct($url, $prefix = null, int $lineNumber = 0)
+    public function __construct($url, ?string $prefix = null, int $lineNumber = 0)
     {
         $this->url = $url;
         $this->prefix = $prefix;
@@ -69,7 +70,7 @@ public function render(OutputFormat $outputFormat): string
     }
 
     /**
-     * @return string
+     * @return CSSString|URL
      */
     public function getUrl()
     {
@@ -85,7 +86,7 @@ public function getPrefix()
     }
 
     /**
-     * @param string $url
+     * @param CSSString|URL $url
      */
     public function setUrl($url): void
     {
diff --git a/src/Rule/Rule.php b/src/Rule/Rule.php
index a20e864d..bbb7c713 100644
--- a/src/Rule/Rule.php
+++ b/src/Rule/Rule.php
@@ -56,11 +56,9 @@ class Rule implements Renderable, Commentable
     protected $comments = [];
 
     /**
-     * @param string $rule
      * @param int<0, max> $lineNumber
-     * @param int $columnNumber
      */
-    public function __construct($rule, int $lineNumber = 0, $columnNumber = 0)
+    public function __construct(string $rule, int $lineNumber = 0, int $columnNumber = 0)
     {
         $this->rule = $rule;
         $this->lineNumber = $lineNumber;
diff --git a/src/RuleSet/AtRuleSet.php b/src/RuleSet/AtRuleSet.php
index a896246b..46562eb1 100644
--- a/src/RuleSet/AtRuleSet.php
+++ b/src/RuleSet/AtRuleSet.php
@@ -27,10 +27,9 @@ class AtRuleSet extends RuleSet implements AtRule
 
     /**
      * @param non-empty-string $type
-     * @param string $arguments
      * @param int<0, max> $lineNumber
      */
-    public function __construct($type, $arguments = '', int $lineNumber = 0)
+    public function __construct(string $type, string $arguments = '', int $lineNumber = 0)
     {
         parent::__construct($lineNumber);
         $this->type = $type;
diff --git a/src/Value/CSSFunction.php b/src/Value/CSSFunction.php
index 3c10900e..aa5e66e7 100644
--- a/src/Value/CSSFunction.php
+++ b/src/Value/CSSFunction.php
@@ -24,12 +24,10 @@ class CSSFunction extends ValueList
     protected $name;
 
     /**
-     * @param string $name
      * @param RuleValueList|array<array-key, Value|string> $arguments
-     * @param string $separator
      * @param int<0, max> $lineNumber
      */
-    public function __construct($name, $arguments, $separator = ',', int $lineNumber = 0)
+    public function __construct(string $name, $arguments, string $separator = ',', int $lineNumber = 0)
     {
         if ($arguments instanceof RuleValueList) {
             $separator = $arguments->getListSeparator();
diff --git a/src/Value/RuleValueList.php b/src/Value/RuleValueList.php
index 9e505979..2cbc1fcc 100644
--- a/src/Value/RuleValueList.php
+++ b/src/Value/RuleValueList.php
@@ -12,10 +12,9 @@
 class RuleValueList extends ValueList
 {
     /**
-     * @param string $separator
      * @param int<0, max> $lineNumber
      */
-    public function __construct($separator = ',', int $lineNumber = 0)
+    public function __construct(string $separator = ',', int $lineNumber = 0)
     {
         parent::__construct([], $separator, $lineNumber);
     }
diff --git a/src/Value/ValueList.php b/src/Value/ValueList.php
index 8a50809d..aed4ec60 100644
--- a/src/Value/ValueList.php
+++ b/src/Value/ValueList.php
@@ -30,10 +30,9 @@ abstract class ValueList extends Value
 
     /**
      * @param array<array-key, Value|string>|Value|string $components
-     * @param string $separator
      * @param int<0, max> $lineNumber
      */
-    public function __construct($components = [], $separator = ',', int $lineNumber = 0)
+    public function __construct($components = [], string $separator = ',', int $lineNumber = 0)
     {
         parent::__construct($lineNumber);
         if (!\is_array($components)) {