diff --git a/src/Client.php b/src/Client.php
index 3adbf4a..f7f46e1 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -72,7 +72,9 @@ protected function doRequestAsync($request)
         $ch = $this->createCurl($request);
         $content = (yield $ch);
         yield CoInterface::RETURN_WITH => $this->processResult($content, $ch);
+        // @codeCoverageIgnoreStart
     }
+    // @codeCoverageIgnoreEnd
 
     protected function createCurl($request)
     {
@@ -98,7 +100,7 @@ protected function createCurl($request)
         }
         $params = $request->getParameters();
         $files = $request->getFiles();
-        if (!$files) {
+        if (!$files && !self::containsCURLFile($params)) {
             $content = http_build_query($params, '', '&', PHP_QUERY_RFC3986);
             curl_setopt($ch, CURLOPT_POSTFIELDS, $content);
             return $ch;
@@ -143,6 +145,9 @@ protected function createHeaders($request)
                 continue;
             }
         }
+        if ($request->getContent() !== null && !preg_grep('/^content-type:/', $headers)) {
+            $headers[] = 'content-type: application/octet-stream';
+        }
         return $headers;
     }
 
@@ -170,12 +175,14 @@ protected function addMultipartFiles(array $files, array &$multipart, $arrayName
                 $multipart[$name] = new \CURLFile($info);
                 continue;
             }
-            if (!isset($info['tmp_name'])) {
+            if (!isset($info['tmp_name']) || is_array($info['tmp_name'])) {
                 $this->addMultipartFiles($info, $multipart, $name);
                 continue;
             }
             if ('' === $info['tmp_name']) {
+                // @codeCoverageIgnoreStart
                 continue;
+                // @codeCoverageIgnoreEnd
             }
             $multipart[$name] = new \CURLFile(
                 $info['tmp_name'],
@@ -198,4 +205,20 @@ protected function addMultipartFields(array $params, array &$multipart, $arrayNa
             $this->addMultipartFields($value, $multipart, $name);
         }
     }
+
+    protected static function containsCURLFile(array $array)
+    {
+        foreach ($array as $item) {
+            if (is_array($item)) {
+                if (self::containsCURLFile($item)) {
+                    return true;
+                }
+                continue;
+            }
+            if ($item instanceof \CURLFile) {
+                return true;
+            }
+        }
+        return false;
+    }
 }
diff --git a/tests/assets/www/json.php b/tests/assets/www/json.php
new file mode 100644
index 0000000..31fbf37
--- /dev/null
+++ b/tests/assets/www/json.php
@@ -0,0 +1,9 @@
+<div class="json"><?php
+
+    $rawpost = file_get_contents('php://input');
+    $rawquery = filter_input(INPUT_SERVER, 'QUERY_STRING');
+    $rawcookie = filter_input(INPUT_SERVER, 'HTTP_COOKIE');
+
+    echo json_encode(compact('_GET', '_POST', '_COOKIE', 'rawpost', 'rawquery', 'rawcookie'));
+
+?></div>
diff --git a/tests/assets/www/upload_form01.php b/tests/assets/www/upload_form01.php
new file mode 100644
index 0000000..d6d8b3f
--- /dev/null
+++ b/tests/assets/www/upload_form01.php
@@ -0,0 +1,11 @@
+<form method="post" action="" enctype="multipart/form-data">
+    <input type="file" name="file[x][y]">
+    <input type="submit" value="submit">
+</form>
+<?php if (isset($_FILES['file']['error']['x']['y']) && is_int($_FILES['file']['error']['x']['y'])): ?>
+<?php if ($_FILES['file']['error']['x']['y'] === UPLOAD_ERR_OK): ?>
+<div id="success">SUCCESS</div>
+<?php else: ?>
+<div id="error">ERROR</div>
+<?php endif; ?>
+<?php endif; ?>
diff --git a/tests/assets/www/upload_form02.php b/tests/assets/www/upload_form02.php
new file mode 100644
index 0000000..ad48373
--- /dev/null
+++ b/tests/assets/www/upload_form02.php
@@ -0,0 +1,11 @@
+<form method="post" action="" enctype="multipart/form-data">
+    <input type="file" name="file[tmp_name][y]">
+    <input type="submit" value="submit">
+</form>
+<?php if (isset($_FILES['file']['error']['tmp_name']['y']) && is_int($_FILES['file']['error']['tmp_name']['y'])): ?>
+<?php if ($_FILES['file']['error']['tmp_name']['y'] === UPLOAD_ERR_OK): ?>
+<div id="success">SUCCESS</div>
+<?php else: ?>
+<div id="error">ERROR</div>
+<?php endif; ?>
+<?php endif; ?>
diff --git a/tests/unit/ClientConfigTest.php b/tests/unit/ClientConfigTest.php
new file mode 100644
index 0000000..c1771df
--- /dev/null
+++ b/tests/unit/ClientConfigTest.php
@@ -0,0 +1,25 @@
+<?php
+
+use mpyw\Coutte\Client;
+use mpyw\Co\Co;
+use mpyw\Co\CoInterface;
+use mpyw\Privator\Proxy;
+use mpyw\Privator\ProxyException;
+
+/**
+ * @requires PHP 7.0
+ */
+class ClientConfigTest extends \Codeception\TestCase\Test {
+
+    use \Codeception\Specify;
+
+    public function testCurlOptionsConfig()
+    {
+        $client = new Client($expected = [
+            CURLOPT_SSL_VERIFYPEER => false,
+            CURLOPT_SSL_VERIFYHOST => false,
+        ]);
+        $actual = array_intersect_key($client->getCurlOptions(), $expected);
+        $this->assertEquals($expected, $actual);
+    }
+}
diff --git a/tests/unit/ClientGetAndPostTest.php b/tests/unit/ClientGetAndPostTest.php
new file mode 100644
index 0000000..b0ad91b
--- /dev/null
+++ b/tests/unit/ClientGetAndPostTest.php
@@ -0,0 +1,51 @@
+<?php
+
+use mpyw\Coutte\Client;
+use mpyw\Co\Co;
+use mpyw\Co\CoInterface;
+use mpyw\Co\CURLException;
+use mpyw\Privator\Proxy;
+use mpyw\Privator\ProxyException;
+
+/**
+ * @requires PHP 7.0
+ */
+class ClientGetAndPostTest extends \Codeception\TestCase\Test {
+
+    use \Codeception\Specify;
+
+    public function getClient()
+    {
+        return new Client([
+            CURLOPT_SSL_VERIFYPEER => false,
+            CURLOPT_SSL_VERIFYHOST => false,
+        ]);
+    }
+
+    public function testInvalid()
+    {
+        $this->setExpectedException(CURLException::class);
+        $client = $this->getClient();
+        $client->request('GET', 'invalid');
+    }
+
+    public function testNormalPost()
+    {
+        $client = $this->getClient();
+        $expected = ['a' => 'b'];
+        $crawler = $client->request('POST', 'http://localhost:8080/json.php', $expected);
+        $json = json_decode($crawler->filter('.json')->text(), true);
+        $this->assertEquals($expected, $json['_POST']);
+    }
+
+    public function testRawPost()
+    {
+        $client = $this->getClient();
+        $expected = 'abcde';
+        $crawler = $client->request('POST', 'http://localhost:8080/json.php', [], [], [], $expected);
+        $json = json_decode($crawler->filter('.json')->text(), true);
+        $this->assertEquals([], $json['_POST']);
+        $this->assertEquals($expected, $json['rawpost']);
+    }
+
+}
diff --git a/tests/unit/ClientPayloadTest.php b/tests/unit/ClientPayloadTest.php
new file mode 100644
index 0000000..629d68a
--- /dev/null
+++ b/tests/unit/ClientPayloadTest.php
@@ -0,0 +1,56 @@
+<?php
+
+use mpyw\Coutte\Client;
+use mpyw\Co\Co;
+use mpyw\Co\CoInterface;
+use mpyw\Privator\Proxy;
+use mpyw\Privator\ProxyException;
+
+/**
+ * @requires PHP 7.0
+ */
+class ClientPayloadTest extends \Codeception\TestCase\Test {
+
+    use \Codeception\Specify;
+
+    public function getClient()
+    {
+        return new Client([
+            CURLOPT_SSL_VERIFYPEER => false,
+            CURLOPT_SSL_VERIFYHOST => false,
+        ]);
+    }
+
+    public function testPayloadHttp()
+    {
+        $client = $this->getClient();
+        $client->request('GET', 'http://localhost:8080/hello.php');
+        $this->assertEquals('Hello', $client->getResponse()->getContent());
+    }
+
+    public function testPayloadHttps()
+    {
+        $client = $this->getClient();
+        $client->request('GET', 'https://localhost:8081/hello.php');
+        $this->assertEquals('Hello', $client->getResponse()->getContent());
+    }
+
+    public function testAsyncPayloadHttp()
+    {
+        Co::wait(function () {
+            $client = $this->getClient();
+            yield $client->requestAsync('GET', 'http://localhost:8080/hello.php');
+            $this->assertEquals('Hello', $client->getResponse()->getContent());
+        });
+    }
+
+    public function testAsyncPayloadHttps()
+    {
+        Co::wait(function () {
+            $client = $this->getClient();
+            yield $client->requestAsync('GET', 'https://localhost:8081/hello.php');
+            $this->assertEquals('Hello', $client->getResponse()->getContent());
+        });
+    }
+
+}
diff --git a/tests/unit/ClientTest.php b/tests/unit/ClientTest.php
deleted file mode 100644
index 2d8088e..0000000
--- a/tests/unit/ClientTest.php
+++ /dev/null
@@ -1,39 +0,0 @@
-<?php
-
-use mpyw\Coutte\Client;
-use mpyw\Co\Co;
-use mpyw\Co\CoInterface;
-use mpyw\Privator\Proxy;
-use mpyw\Privator\ProxyException;
-
-/**
- * @requires PHP 7.0
- */
-class ClientTest extends \Codeception\TestCase\Test {
-
-    use \Codeception\Specify;
-    private static $pid;
-
-    public function getClient()
-    {
-        return new Client([
-            CURLOPT_SSL_VERIFYPEER => false,
-            CURLOPT_SSL_VERIFYHOST => false,
-        ]);
-    }
-
-    public function testPayloadHttp()
-    {
-        $c = $this->getClient();
-        $c->request('GET', 'http://localhost:8080/hello.php');
-        $this->assertEquals('Hello', $c->getResponse()->getContent());
-    }
-
-    public function testPayloadHttps()
-    {
-        $c = $this->getClient();
-        $c->request('GET', 'https://localhost:8081/hello.php');
-        $this->assertEquals('Hello', $c->getResponse()->getContent());
-    }
-
-}
diff --git a/tests/unit/ClientUploadTest.php b/tests/unit/ClientUploadTest.php
new file mode 100644
index 0000000..699abb7
--- /dev/null
+++ b/tests/unit/ClientUploadTest.php
@@ -0,0 +1,106 @@
+<?php
+
+use mpyw\Coutte\Client;
+use mpyw\Co\Co;
+use mpyw\Co\CoInterface;
+use mpyw\Privator\Proxy;
+use mpyw\Privator\ProxyException;
+
+/**
+ * @requires PHP 7.0
+ */
+class ClientUploadTest extends \Codeception\TestCase\Test {
+
+    use \Codeception\Specify;
+
+    public function getClient()
+    {
+        return new Client([
+            CURLOPT_SSL_VERIFYPEER => false,
+            CURLOPT_SSL_VERIFYHOST => false,
+        ]);
+    }
+
+    public function testUpload01()
+    {
+        $client = $this->getClient();
+        $crawler = $client->request('GET', 'http://localhost:8080/upload_form01.php');
+        $form = $crawler->filter('form')->form([
+            'file[x][y]' => __FILE__,
+        ]);
+        $crawler = $client->submit($form);
+        $this->assertEquals('SUCCESS', $crawler->filter('#success')->text());
+    }
+
+    public function testUpload02()
+    {
+        $client = $this->getClient();
+        $crawler = $client->request('GET', 'http://localhost:8080/upload_form02.php');
+        $form = $crawler->filter('form')->form([
+            'file[tmp_name][y]' => __FILE__,
+        ]);
+        $crawler = $client->submit($form);
+        $this->assertEquals('SUCCESS', $crawler->filter('#success')->text());
+    }
+
+    public function testUpload03()
+    {
+        $this->setExpectedException(
+            PHPUnit_Framework_Exception::class,
+            'is_readable() expects parameter 1 to be a valid path, object given'
+        );
+        $client = $this->getClient();
+        $crawler = $client->request('GET', 'http://localhost:8080/upload_form01.php');
+        $form = $crawler->filter('form')->form([
+            'file[x][y]' => new CURLFile(__FILE__),
+        ]);
+    }
+
+    public function testUpload04()
+    {
+        $client = $this->getClient();
+        $crawler = $client->request(
+            'POST',
+            'http://localhost:8080/upload_form01.php',
+            [],
+            [
+                'file[x]' => [
+                    'y' => new CURLFile(__FILE__)
+                ]
+            ]
+        );
+        $this->assertEquals('SUCCESS', $crawler->filter('#success')->text());
+    }
+
+    public function testUpload05()
+    {
+        $client = $this->getClient();
+        $crawler = $client->request(
+            'POST',
+            'http://localhost:8080/upload_form01.php',
+            [],
+            [
+                'file[x]' => [
+                    'y' => __FILE__,
+                ]
+            ]
+        );
+        $this->assertEquals('SUCCESS', $crawler->filter('#success')->text());
+    }
+
+    public function testUpload06()
+    {
+        $client = $this->getClient();
+        $crawler = $client->request(
+            'POST',
+            'http://localhost:8080/upload_form01.php',
+            [
+                [],
+                'file[x]' => [
+                    'y' => new CURLFile(__FILE__)
+                ]
+            ]
+        );
+        $this->assertEquals('SUCCESS', $crawler->filter('#success')->text());
+    }
+}