diff --git a/src/CSSList/CSSList.php b/src/CSSList/CSSList.php
index 24714834..946740a4 100644
--- a/src/CSSList/CSSList.php
+++ b/src/CSSList/CSSList.php
@@ -32,7 +32,7 @@
 abstract class CSSList implements Renderable, Commentable
 {
     /**
-     * @var array<array-key, Comment> $aComments
+     * @var array<array-key, Comment>
      */
     protected $aComments;
 
@@ -57,10 +57,10 @@ public function __construct($iLineNo = 0)
     }
 
     /**
-     * @throws SourceException
-     * @throws UnexpectedTokenException
-     *
      * @return void
+     *
+     * @throws UnexpectedTokenException
+     * @throws SourceException
      */
     public static function parseList(ParserState $oParserState, CSSList $oList)
     {
@@ -451,6 +451,8 @@ public function getContents()
 
     /**
      * @param array<array-key, Comment> $aComments
+     *
+     * @return void
      */
     public function addComments(array $aComments)
     {
@@ -467,6 +469,8 @@ public function getComments()
 
     /**
      * @param array<array-key, Comment> $aComments
+     *
+     * @return void
      */
     public function setComments(array $aComments)
     {
diff --git a/src/Comment/Commentable.php b/src/Comment/Commentable.php
index f9eb5e51..5e450bfb 100644
--- a/src/Comment/Commentable.php
+++ b/src/Comment/Commentable.php
@@ -5,17 +5,21 @@
 interface Commentable
 {
     /**
-     * @param array $aComments Array of comments.
+     * @param array<array-key, Comment> $aComments
+     *
+     * @return void
      */
     public function addComments(array $aComments);
 
     /**
-     * @return array
+     * @return array<array-key, Comment>
      */
     public function getComments();
 
     /**
-     * @param array $aComments Array containing Comment objects.
+     * @param array<array-key, Comment> $aComments
+     *
+     * @return void
      */
     public function setComments(array $aComments);
 }
diff --git a/src/Property/CSSNamespace.php b/src/Property/CSSNamespace.php
index 30957970..269ad2a1 100644
--- a/src/Property/CSSNamespace.php
+++ b/src/Property/CSSNamespace.php
@@ -2,6 +2,7 @@
 
 namespace Sabberworm\CSS\Property;
 
+use Sabberworm\CSS\Comment\Comment;
 use Sabberworm\CSS\OutputFormat;
 
 /**
@@ -15,6 +16,9 @@ class CSSNamespace implements AtRule
 
     private $iLineNo;
 
+    /**
+     * @var array<array-key, Comment>
+     */
     protected $aComments;
 
     public function __construct($mUrl, $sPrefix = null, $iLineNo = 0)
@@ -89,16 +93,29 @@ public function atRuleArgs()
         return $aResult;
     }
 
+    /**
+     * @param array<array-key, Comment> $aComments
+     *
+     * @return void
+     */
     public function addComments(array $aComments)
     {
         $this->aComments = array_merge($this->aComments, $aComments);
     }
 
+    /**
+     * @return array<array-key, Comment>
+     */
     public function getComments()
     {
         return $this->aComments;
     }
 
+    /**
+     * @param array<array-key, Comment> $aComments
+     *
+     * @return void
+     */
     public function setComments(array $aComments)
     {
         $this->aComments = $aComments;
diff --git a/src/Property/Import.php b/src/Property/Import.php
index beca0ff2..0bda7766 100644
--- a/src/Property/Import.php
+++ b/src/Property/Import.php
@@ -2,6 +2,7 @@
 
 namespace Sabberworm\CSS\Property;
 
+use Sabberworm\CSS\Comment\Comment;
 use Sabberworm\CSS\OutputFormat;
 use Sabberworm\CSS\Value\URL;
 
@@ -26,7 +27,7 @@ class Import implements AtRule
     protected $iLineNo;
 
     /**
-     * @var array
+     * @var array<array-key, Comment>
      */
     protected $aComments;
 
@@ -97,16 +98,29 @@ public function atRuleArgs()
         return $aResult;
     }
 
+    /**
+     * @param array<array-key, Comment> $aComments
+     *
+     * @return void
+     */
     public function addComments(array $aComments)
     {
         $this->aComments = array_merge($this->aComments, $aComments);
     }
 
+    /**
+     * @return array<array-key, Comment>
+     */
     public function getComments()
     {
         return $this->aComments;
     }
 
+    /**
+     * @param array<array-key, Comment> $aComments
+     *
+     * @return void
+     */
     public function setComments(array $aComments)
     {
         $this->aComments = $aComments;
diff --git a/src/Property/Selector.php b/src/Property/Selector.php
index c0aad2a5..3aee4ac4 100644
--- a/src/Property/Selector.php
+++ b/src/Property/Selector.php
@@ -60,15 +60,30 @@ class Selector
 	)$
 	/ux';
 
+    /**
+     * @var string
+     */
     private $sSelector;
 
+    /**
+     * @var int|null
+     */
     private $iSpecificity;
 
+    /**
+     * @param string $sSelector
+     *
+     * @return bool
+     */
     public static function isValid($sSelector)
     {
         return preg_match(static::SELECTOR_VALIDATION_RX, $sSelector);
     }
 
+    /**
+     * @param string $sSelector
+     * @param bool $bCalculateSpecificity
+     */
     public function __construct($sSelector, $bCalculateSpecificity = false)
     {
         $this->setSelector($sSelector);
@@ -77,22 +92,36 @@ public function __construct($sSelector, $bCalculateSpecificity = false)
         }
     }
 
+    /**
+     * @return string
+     */
     public function getSelector()
     {
         return $this->sSelector;
     }
 
+    /**
+     * @param string $sSelector
+     *
+     * @return void
+     */
     public function setSelector($sSelector)
     {
         $this->sSelector = trim($sSelector);
         $this->iSpecificity = null;
     }
 
+    /**
+     * @return string
+     */
     public function __toString()
     {
         return $this->getSelector();
     }
 
+    /**
+     * @return int
+     */
     public function getSpecificity()
     {
         if ($this->iSpecificity === null) {
diff --git a/src/RuleSet/RuleSet.php b/src/RuleSet/RuleSet.php
index 614ed6f7..78486814 100644
--- a/src/RuleSet/RuleSet.php
+++ b/src/RuleSet/RuleSet.php
@@ -2,6 +2,7 @@
 
 namespace Sabberworm\CSS\RuleSet;
 
+use Sabberworm\CSS\Comment\Comment;
 use Sabberworm\CSS\Comment\Commentable;
 use Sabberworm\CSS\OutputFormat;
 use Sabberworm\CSS\Parsing\ParserState;
@@ -19,6 +20,9 @@ abstract class RuleSet implements Renderable, Commentable
 
     protected $iLineNo;
 
+    /**
+     * @var array<array-key, Comment>
+     */
     protected $aComments;
 
     public function __construct($iLineNo = 0)
@@ -265,7 +269,9 @@ public function render(OutputFormat $oOutputFormat)
     }
 
     /**
-     * @param array $aComments Array of comments.
+     * @param array<array-key, Comment> $aComments
+     *
+     * @return void
      */
     public function addComments(array $aComments)
     {
@@ -273,7 +279,7 @@ public function addComments(array $aComments)
     }
 
     /**
-     * @return array
+     * @return array<array-key, Comment>
      */
     public function getComments()
     {
@@ -281,7 +287,9 @@ public function getComments()
     }
 
     /**
-     * @param array $aComments Array containing Comment objects.
+     * @param array<array-key, Comment> $aComments
+     *
+     * @return void
      */
     public function setComments(array $aComments)
     {