diff --git a/composer.json b/composer.json
index 17275d6..93bffa5 100644
--- a/composer.json
+++ b/composer.json
@@ -20,7 +20,10 @@
   "autoload": {
     "psr-4": {
       "AlfacodeTeam\\PhpIoCli\\": "src/"
-    }
+    },
+    "files": [
+      "src/mb_polyfill.php"
+    ]
   },
   "autoload-dev": {
     "psr-4": {
diff --git a/src/AbstractCommand.php b/src/AbstractCommand.php
index 851053a..6d8f4cf 100644
--- a/src/AbstractCommand.php
+++ b/src/AbstractCommand.php
@@ -45,7 +45,7 @@ abstract class AbstractCommand
 
     private bool $rethrowExceptions = false;
 
-    final public function __construct()
+    public function __construct()
     {
         $this->configure();
 
diff --git a/src/Internal/MbTrim.php b/src/Internal/MbTrim.php
new file mode 100644
index 0000000..7edbbf8
--- /dev/null
+++ b/src/Internal/MbTrim.php
@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AlfacodeTeam\PhpIoCli\Internal;
+
+/**
+ * Backing implementation for the mb_trim/mb_ltrim/mb_rtrim polyfills (PHP < 8.4).
+ *
+ * @internal
+ */
+final class MbTrim
+{
+    /** Default whitespace set, matching the native PHP 8.4 mb_trim behaviour. */
+    private const DEFAULT = " \f\n\r\t\x0B\x00";
+
+    public static function run(string $string, ?string $characters, bool $left, bool $right): string
+    {
+        $characters ??= self::DEFAULT;
+
+        if ($characters === '') {
+            return $string;
+        }
+
+        // Split the character list into individual (possibly multibyte) characters.
+        $chars = preg_split('//u', $characters, -1, PREG_SPLIT_NO_EMPTY);
+        if ($chars === false || $chars === []) {
+            return $string;
+        }
+
+        $class = '';
+        foreach ($chars as $char) {
+            $class .= preg_quote($char, '/');
+        }
+
+        $pattern = '';
+        if ($left) {
+            $pattern .= '^[' . $class . ']+';
+        }
+        if ($left && $right) {
+            $pattern .= '|';
+        }
+        if ($right) {
+            $pattern .= '[' . $class . ']+$';
+        }
+
+        $result = preg_replace('/' . $pattern . '/u', '', $string);
+
+        return $result ?? $string;
+    }
+}
diff --git a/src/mb_polyfill.php b/src/mb_polyfill.php
new file mode 100644
index 0000000..24d6dc0
--- /dev/null
+++ b/src/mb_polyfill.php
@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Polyfills for the multibyte trim functions introduced in PHP 8.4.
+ * This library targets PHP 8.2+, so on PHP < 8.4 these functions are absent.
+ * The implementations mirror the native behaviour: when no character list is
+ * supplied they strip the same default whitespace set as the native functions.
+ */
+
+if (!function_exists('mb_trim')) {
+    /**
+     * @param string      $string
+     * @param string|null $characters
+     * @param string|null $encoding
+     */
+    function mb_trim(string $string, ?string $characters = null, ?string $encoding = null): string
+    {
+        return \AlfacodeTeam\PhpIoCli\Internal\MbTrim::run($string, $characters, true, true);
+    }
+}
+
+if (!function_exists('mb_ltrim')) {
+    function mb_ltrim(string $string, ?string $characters = null, ?string $encoding = null): string
+    {
+        return \AlfacodeTeam\PhpIoCli\Internal\MbTrim::run($string, $characters, true, false);
+    }
+}
+
+if (!function_exists('mb_rtrim')) {
+    function mb_rtrim(string $string, ?string $characters = null, ?string $encoding = null): string
+    {
+        return \AlfacodeTeam\PhpIoCli\Internal\MbTrim::run($string, $characters, false, true);
+    }
+}