diff --git a/include/image_fetch.php b/include/image_fetch.php
index efc79a5..b284c70 100644
--- a/include/image_fetch.php
+++ b/include/image_fetch.php
@@ -42,15 +42,23 @@ final class ImageFetch
 
   /** Fehlercodes, bei denen sich ein Retry lohnt */
   private static array $RETRY_HTTP = [429, 500, 502, 503, 504, 520, 521, 522, 523, 524];
-  private static array $RETRY_CURL = [
-    CURLE_OPERATION_TIMEDOUT,
-    CURLE_COULDNT_RESOLVE_HOST,
-    CURLE_COULDNT_CONNECT,
-    CURLE_RECV_ERROR,
-    CURLE_SEND_ERROR,
-    CURLE_GOT_NOTHING,
-    CURLE_HTTP2_STREAM, // HTTP/2 stream error/RESET
-  ];
+
+  private static function retryCurlCodes(): array
+  {
+    $list = [
+      \defined('CURLE_OPERATION_TIMEDOUT')      ? \constant('CURLE_OPERATION_TIMEDOUT')      : null,
+      \defined('CURLE_COULDNT_RESOLVE_HOST')    ? \constant('CURLE_COULDNT_RESOLVE_HOST')    : null,
+      \defined('CURLE_COULDNT_CONNECT')         ? \constant('CURLE_COULDNT_CONNECT')         : null,
+      \defined('CURLE_RECV_ERROR')              ? \constant('CURLE_RECV_ERROR')              : null,
+      \defined('CURLE_SEND_ERROR')              ? \constant('CURLE_SEND_ERROR')              : null,
+      \defined('CURLE_GOT_NOTHING')             ? \constant('CURLE_GOT_NOTHING')             : null,
+      \defined('CURLE_HTTP2_STREAM')            ? \constant('CURLE_HTTP2_STREAM')            : null, // nur wenn vorhanden
+      \defined('CURLE_HTTP2')                   ? \constant('CURLE_HTTP2')                   : null, // manche Builds haben nur den
+    ];
+    // Nulls rausfiltern
+    return array_values(array_filter($list, static fn($v) => $v !== null));
+  }
+
 
   /** Öffentliche API */
   public static function download(string $url, array $opt = []): array
@@ -172,8 +180,8 @@ final class ImageFetch
         },
         CURLOPT_ACCEPT_ENCODING  => '',         // gzip/br zulassen
       ];
-      if ($cfg['ip_resolve_v4']) {
-        $opts[CURLOPT_IPRESOLVE] = CURL_IPRESOLVE_V4;
+      if (!empty($cfg['ip_resolve_v4']) && \defined('CURLOPT_IPRESOLVE') && \defined('CURL_IPRESOLVE_V4')) {
+        $opts[CURLOPT_IPRESOLVE] = \constant('CURL_IPRESOLVE_V4');
       }
       if ($referer) {
         $opts[CURLOPT_REFERER] = $referer;
@@ -224,7 +232,7 @@ final class ImageFetch
         // Fehler oder Non-2xx → ggf. retry
         @unlink($tmp);
         $doRetry = ($i + 1) < $attempts &&
-                   (in_array($http, self::$RETRY_HTTP, true) || in_array($cerr, self::$RETRY_CURL, true) || $http === 0);
+                   (in_array($http, self::$RETRY_HTTP, true) || in_array($cerr, self::retryCurlCodes(), true) || $http === 0);
         error_log("{$cfg['log_prefix']} fail http=$http curl={$cerr}:{$cerrStr} ua#{$i} retry=".($doRetry?'1':'0')." url=$url");
       }