diff --git a/src/Std/Lib/Activitypub.php b/src/Std/Lib/Activitypub.php
index 127eb00..196bb63 100644
--- a/src/Std/Lib/Activitypub.php
+++ b/src/Std/Lib/Activitypub.php
@@ -39,6 +39,7 @@ namespace Std\Lib;
 
 use Std\Lib\Curl;
 use LogType;
+use Uri\Rfc3986;
 
 /**
  * ActivityPubプロトコルの実装クラス
@@ -445,10 +446,10 @@ class ActivityPub {
     $body = json_encode($activity, JSON_UNESCAPED_SLASHES);
     $digest = base64_encode(hash('sha256', $body, true));
     $date = gmdate('D, d M Y H:i:s \G\M\T');
-    $host = parse_url($inboxUrl, PHP_URL_HOST);
+    $uri = new Uri($inboxUrl);
 
     $headers = [
-      'Host' => $host,
+      'Host' => $uri->getHost().($uri->getPort() ? ':'.$uri->getPort() : ''),
       'Date' => $date,
       'Content-Type' => 'application/activity+json',
       'Digest' => "SHA-256=$digest",
diff --git a/src/Std/Lib/Curl.php b/src/Std/Lib/Curl.php
index 819e447..043b77f 100644
--- a/src/Std/Lib/Curl.php
+++ b/src/Std/Lib/Curl.php
@@ -38,6 +38,7 @@ OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 namespace Std\Lib;
 
 use Result;
+use Uri\Rfc3986;
 
 /**
  * php_curlへの依存を排除するための独自のCURL実装
@@ -354,19 +355,18 @@ class Curl {
         fwrite($this->stderr, "* 接続中: {$currentUrl}\n");
       }
 
-      $parsed = parse_url($currentUrl);
-      if (!$parsed) {
+      $uri = new Uri($currentUrl);
+      if (!$uri) {
         $this->responseError = "無効なURL: {$currentUrl}";
         return Result::Error($this->responseError);
       }
 
-      $scheme = isset($parsed['scheme']) ? strtolower($parsed['scheme']) : 'http';
-      $host = $parsed['host'];
-      $port = isset($parsed['port']) 
-        ? $parsed['port'] : ($scheme === 'https' ? 443 : 80);
-      $path = isset($parsed['path']) ? $parsed['path'] : '/';
-      if (isset($parsed['query'])) {
-        $path .= '?'.$parsed['query'];
+      $scheme = $uri->getScheme() ?? 'http';
+      $port = $uri->getPort() ?? ($scheme === 'https' ? 443 : 80);
+      $path = $uri->getPath();
+      if ($path === '') $path = '/';
+      if (isset($uri->getQuery())) {
+        $path .= '?'.$uri->getQuery();
       }
 
       // 認証
@@ -404,7 +404,7 @@ class Curl {
       }
 
       $request = "{$method} {$path} HTTP/1.1\r\n";
-      $request .= "Host: {$host}\r\n";
+      $request .= "Host: {$uri->getHost()}\r\n";
       $request .= "User-Agent: {$this->userAgent}\r\n";
       $request .= "{$accept}\r\n";
       $request .= "Connection: close\r\n";
@@ -462,7 +462,7 @@ class Curl {
         $context = stream_context_create(['ssl' => $sslOptions]);
         
         $socket = @stream_socket_client(
-          "tls://{$host}:{$port}",
+          "tls://{$uri->getHost()}:{$port}",
           $errno,
           $errstr,
           $this->timeout,
@@ -470,7 +470,7 @@ class Curl {
           $context
         );
       } else {
-        $socket = @fsockopen($host, $port, $errno, $errstr, $this->timeout);
+        $socket = @fsockopen($uri->getHost(), $port, $errno, $errstr, $this->timeout);
       }
 
       if (!$socket) {
@@ -637,9 +637,9 @@ class Curl {
 
         if (strpos($redirectUrl, 'http') !== 0) {
           if ($redirectUrl[0] === '/') {
-            $parsed = parse_url($currentUrl);
-            $redirectUrl = $parsed['scheme'].'://'.$parsed['host']
-              .(isset($parsed['port']) ? ':'.$parsed['port'] : '')
+            $uri = new Uri($currentUrl);
+            $redirectUrl = $uri->getScheme().'://'.$uri->getHost()
+              .(isset($uri->getPort()) ? ':'.$uri->getPort() : '')
               .$redirectUrl;
           } else {
             $redirectUrl = dirname($currentUrl).'/'.$redirectUrl;
diff --git a/src/Std/Lib/Tester.php b/src/Std/Lib/Tester.php
index 90e9be9..35359de 100644
--- a/src/Std/Lib/Tester.php
+++ b/src/Std/Lib/Tester.php
@@ -407,6 +407,7 @@ class Tester {
    */
   public function assertArrayHasKey(mixed $key, array $array,
                                     ?string $message = null): Tester {
+    if (NULL === $key) throw new AssertionFailedException("配列鍵がありません");
     if (!is_array($array) && !($array instanceof \ArrayAccess)) {
       throw new AssertionFailedException(
         '第2引数は配列又はArrayAccessを実装している必要があります');
diff --git a/util.php b/util.php
index d1236c3..f09bed0 100644
--- a/util.php
+++ b/util.php
@@ -470,11 +470,4 @@ function align_down(int $val): int {
 
   while ($lower * 2 <= $val) $lower *= 2;
   return $lower;
-}
-
-// PHP 8.3と8.4の場合
-if (!function_exists('array_last')) {
-  function array_last(array $array): mixed {
-    return $array === [] ? null : $array[array_key_last($array)];
-  }
 }
\ No newline at end of file
diff --git a/view/common/header.maron b/view/common/header.maron
index d3e96b3..9b88a36 100644
--- a/view/common/header.maron
+++ b/view/common/header.maron
@@ -20,7 +20,7 @@
 {@ endif @}
 {@ endif @}
   <meta name="description" content="{{ $description }}" />
-  <meta name="keywords" content="{{ SITEINFO['tags'].(isset($meta->category) ? ',' : '') }}{@ if (isset($meta) && isset($meta->category)) @}{@ foreach ($meta->category as $k => $cat) @}{{ $cat.($k === array_key_last($meta->category) ? '' : ',') }}{@ endforeach @}{@ endif @}" />
+  <meta name="keywords" content="{{ SITEINFO['tags'].(isset($meta->category) ? ',' : '') }}{@ if (isset($meta) && isset($meta->category)) @}{@ foreach ($meta->category as $k => $cat) @}{{ $cat.($k === array_last($meta->category) ? '' : ',') }}{@ endforeach @}{@ endif @}" />
 
   <meta property="og:title" content="{{ SITEINFO['title'] }}: {{ $pagetit }}" />
   <meta property="og:description" content="{{ $description }}" />