diff --git a/src/File.php b/src/File.php
index e61b2bdf..0981ebf9 100644
--- a/src/File.php
+++ b/src/File.php
@@ -111,33 +111,15 @@ public function __construct(string $url, int $timeout = 10, int $redirects = 5,
             if (!$force_fsockopen && function_exists('curl_exec')) {
                 $this->method = \SimplePie\SimplePie::FILE_SOURCE_REMOTE | \SimplePie\SimplePie::FILE_SOURCE_CURL;
                 $fp = curl_init();
-                if (is_array($curl_options[CURLOPT_HTTPHEADER] ?? null)) {
-                    // Save the original casing of HTTP headers
-                    $headers_keys = array_combine(array_map('strtolower', array_keys($headers)), array_keys($headers)) ?: [];
-                    // Merge HTTP headers case-insensitively from cURL options with the ones from the dedicated parameter
-                    $headers = array_change_key_case($headers, CASE_LOWER);
-                    foreach ($curl_options[CURLOPT_HTTPHEADER] as $header) {
-                        if (is_string($header)) {
-                            $parts = explode(':', $header, 2);
-                            if (count($parts) >= 2) {
-                                $key = trim($parts[0]);
-                                $headers_keys[strtolower($key)] = $key;
-                                $headers[strtolower($key)] = trim($parts[1]);
-                            }
-                        }
-                    }
-                    // Restore original casing of HTTP headers
-                    foreach ($headers_keys as $lower_key => $original_key) {
-                        if ($lower_key !== $original_key && isset($headers[$lower_key])) {
-                            $headers[$original_key] = $headers[$lower_key];
-                            unset($headers[$lower_key]);
-                        }
-                    }
-                }
-                unset($curl_options[CURLOPT_HTTPHEADER]);
-                $headers_inlined = [];
+                $headers2 = [];
                 foreach ($headers as $key => $value) {
-                    $headers_inlined[] = "$key: $value";
+                    $headers2[] = "$key: $value";
+                }
+                if (isset($curl_options[CURLOPT_HTTPHEADER])) {
+                    if (is_array($curl_options[CURLOPT_HTTPHEADER])) {
+                        $headers2 = array_merge($headers2, $curl_options[CURLOPT_HTTPHEADER]);
+                    }
+                    unset($curl_options[CURLOPT_HTTPHEADER]);
                 }
                 if (version_compare(\SimplePie\Misc::get_curl_version(), '7.10.5', '>=')) {
                     curl_setopt($fp, CURLOPT_ENCODING, '');
@@ -149,7 +131,7 @@ public function __construct(string $url, int $timeout = 10, int $redirects = 5,
                 curl_setopt($fp, CURLOPT_CONNECTTIMEOUT, $timeout);
                 // curl_setopt($fp, CURLOPT_REFERER, \SimplePie\Misc::url_remove_credentials($url)); // FreshRSS removed
                 curl_setopt($fp, CURLOPT_USERAGENT, $useragent);
-                curl_setopt($fp, CURLOPT_HTTPHEADER, $headers_inlined);
+                curl_setopt($fp, CURLOPT_HTTPHEADER, $headers2);
                 $responseHeaders = '';
                 curl_setopt($fp, CURLOPT_HEADERFUNCTION, function ($ch, string $header) use (&$responseHeaders) {
                     $responseHeaders .= $header;