diff --git a/src/Components/Inlines/Emphasis.php b/src/Components/Inlines/Emphasis.php
index c98d89e..08bae6f 100644
--- a/src/Components/Inlines/Emphasis.php
+++ b/src/Components/Inlines/Emphasis.php
@@ -21,14 +21,12 @@ final class Emphasis implements Inline
     /** @var 'em'|'strong' */
     private $type;
 
-    /** @var array{*: string, _: string} */
-    private static $STRONG_REGEX = [
+    private const STRONG_REGEX = [
         '*' => '/^[*]{2}((?:\\\\\*|[^*]|[*][^*]*+[*])+?)[*]{2}(?![*])/s',
         '_' => '/^__((?:\\\\_|[^_]|_[^_]*+_)+?)__(?!_)/us',
     ];
 
-    /** @var array{*: string, _: string} */
-    private static $EM_REGEX = [
+    private const EM_REGEX = [
         '*' => '/^[*]((?:\\\\\*|[^*]|[*][*][^*]+?[*][*])+?)[*](?![*])/s',
         '_' => '/^_((?:\\\\_|[^_]|__[^_]*__)+?)_(?!_)\b/us',
     ];
@@ -58,9 +56,9 @@ final class Emphasis implements Inline
             return null;
         }
 
-        if (\preg_match(self::$STRONG_REGEX[$marker], $Excerpt->text(), $matches)) {
+        if (\preg_match(self::STRONG_REGEX[$marker], $Excerpt->text(), $matches)) {
             $emphasis = 'strong';
-        } elseif (\preg_match(self::$EM_REGEX[$marker], $Excerpt->text(), $matches)) {
+        } elseif (\preg_match(self::EM_REGEX[$marker], $Excerpt->text(), $matches)) {
             $emphasis = 'em';
         } else {
             return null;
diff --git a/src/Configurables/BlockTypes.php b/src/Configurables/BlockTypes.php
index c7a770f..694fc46 100644
--- a/src/Configurables/BlockTypes.php
+++ b/src/Configurables/BlockTypes.php
@@ -17,8 +17,7 @@ use Erusev\Parsedown\Configurable;
 
 final class BlockTypes implements Configurable
 {
-    /** @var array<array-key, array<int, class-string<Block>>> */
-    private static $defaultBlockTypes = [
+    private const DEFAULT_BLOCK_TYPES = [
         '#' => [Header::class],
         '*' => [Rule::class, TList::class],
         '+' => [TList::class],
@@ -44,8 +43,7 @@ final class BlockTypes implements Configurable
         '~' => [FencedCode::class],
     ];
 
-    /** @var array<int, class-string<Block>> */
-    private static $defaultUnmarkedBlockTypes = [
+    private const DEFAULT_UNMARKED_BLOCK_TYPES = [
         IndentedCode::class,
     ];
 
@@ -69,8 +67,8 @@ final class BlockTypes implements Configurable
     public static function initial()
     {
         return new self(
-            self::$defaultBlockTypes,
-            self::$defaultUnmarkedBlockTypes
+            self::DEFAULT_BLOCK_TYPES,
+            self::DEFAULT_UNMARKED_BLOCK_TYPES
         );
     }
 
diff --git a/src/Configurables/InlineTypes.php b/src/Configurables/InlineTypes.php
index d8b09fb..8a61169 100644
--- a/src/Configurables/InlineTypes.php
+++ b/src/Configurables/InlineTypes.php
@@ -20,8 +20,7 @@ use Erusev\Parsedown\Configurable;
 
 final class InlineTypes implements Configurable
 {
-    /** @var array<array-key, array<int, class-string<Inline>>> */
-    private static $defaultInlineTypes = [
+    private const DEFAULT_INLINE_TYPES = [
         '!' => [Image::class],
         '*' => [Emphasis::class],
         '_' => [Emphasis::class],
@@ -53,7 +52,7 @@ final class InlineTypes implements Configurable
     /** @return self */
     public static function initial()
     {
-        return new self(self::$defaultInlineTypes);
+        return new self(self::DEFAULT_INLINE_TYPES);
     }
 
     /**
diff --git a/src/Html/Renderables/Element.php b/src/Html/Renderables/Element.php
index 627adb1..14ef739 100644
--- a/src/Html/Renderables/Element.php
+++ b/src/Html/Renderables/Element.php
@@ -10,8 +10,7 @@ final class Element implements Renderable
 {
     use CanonicalStateRenderable;
 
-    /** @var array<string, true> */
-    public static $TEXT_LEVEL_ELEMENTS = [
+    const TEXT_LEVEL_ELEMENTS = [
         'a' => true,
         'b' => true,
         'i' => true,
@@ -167,7 +166,7 @@ final class Element implements Renderable
                 foreach ($this->Contents as $C) {
                     if (
                         $C instanceof Element
-                        && ! \array_key_exists(\strtolower($C->name()), self::$TEXT_LEVEL_ELEMENTS)
+                        && ! \array_key_exists(\strtolower($C->name()), self::TEXT_LEVEL_ELEMENTS)
                     ) {
                         $html .= "\n";
                     }
@@ -179,7 +178,7 @@ final class Element implements Renderable
 
                 if (
                     $Last instanceof Element
-                    && ! \array_key_exists(\strtolower($Last->name()), self::$TEXT_LEVEL_ELEMENTS)
+                    && ! \array_key_exists(\strtolower($Last->name()), self::TEXT_LEVEL_ELEMENTS)
                 ) {
                     $html .= "\n";
                 }
diff --git a/src/Html/Sanitisation/UrlSanitiser.php b/src/Html/Sanitisation/UrlSanitiser.php
index daefc70..47571a8 100644
--- a/src/Html/Sanitisation/UrlSanitiser.php
+++ b/src/Html/Sanitisation/UrlSanitiser.php
@@ -4,8 +4,7 @@ namespace Erusev\Parsedown\Html\Sanitisation;
 
 final class UrlSanitiser
 {
-    /** @var string[] */
-    private static $COMMON_SCHEMES = [
+    private const COMMON_SCHEMES = [
         'http://',
         'https://',
         'ftp://',
@@ -33,7 +32,7 @@ final class UrlSanitiser
     public static function filter($url, $permittedSchemes = null)
     {
         if (! isset($permittedSchemes)) {
-            $permittedSchemes = self::$COMMON_SCHEMES;
+            $permittedSchemes = self::COMMON_SCHEMES;
         }
 
         foreach ($permittedSchemes as $scheme) {
diff --git a/tests/CommonMarkTestWeak.php b/tests/CommonMarkTestWeak.php
index 22a4470..c4dc857 100644
--- a/tests/CommonMarkTestWeak.php
+++ b/tests/CommonMarkTestWeak.php
@@ -28,7 +28,7 @@ class CommonMarkTestWeak extends CommonMarkTestStrict
      */
     public function __construct($name = null, array $data = [], $dataName = '')
     {
-        $textLevelElements = \array_keys(Element::$TEXT_LEVEL_ELEMENTS);
+        $textLevelElements = \array_keys(Element::TEXT_LEVEL_ELEMENTS);
 
         \array_walk(
             $textLevelElements,