diff -ru src/CurlDownloader.php src/CurlDownloader.php
--- src/CurlDownloader.php	2019-04-15 14:25:16.687307074 +0000
+++ src/CurlDownloader.php	2019-04-15 14:25:17.543284269 +0000
@@ -63,12 +63,12 @@
         $params = stream_context_get_params($context);
 
         $ch = curl_init();
-        $hd = fopen('php://temp/maxmemory:32768', 'w+b');
-        if ($file && !$fd = @fopen($file.'~', 'w+b')) {
+        $hd = fopen('php://temp/maxmemory:32768', 'w+');
+        if ($file && !$fd = @fopen($file.'~', 'w+')) {
             $file = null;
         }
         if (!$file) {
-            $fd = @fopen('php://temp/maxmemory:524288', 'w+b');
+            $fd = @fopen('php://temp/maxmemory:524288', 'w+');
         }
         $headers = array_diff($params['options']['http']['header'], ['Connection: close']);
 
@@ -167,7 +167,7 @@
             }
         } finally {
             if ($file && !isset($this->exceptions[(int) $ch])) {
-                $fd = fopen($file, 'rb');
+                $fd = fopen($file, 'r');
             }
             unset($this->jobs[(int) $ch], $this->exceptions[(int) $ch]);
             curl_multi_remove_handle($this->multiHandle, $ch);