diff --git a/src/Mailgun/Connection/RestClient.php b/src/Mailgun/Connection/RestClient.php
index af1dfe3..849b981 100644
--- a/src/Mailgun/Connection/RestClient.php
+++ b/src/Mailgun/Connection/RestClient.php
@@ -133,9 +133,10 @@ class RestClient
         $postDataMultipart = [];
         foreach ($postData as $key => $value) {
             if (is_array($value)) {
+                $index = 0;
                 foreach ($value as $subValue) {
                     $postDataMultipart[] = [
-                        'name'     => $key,
+                        'name'     => sprintf('%s[%d]', $key, $index++),
                         'contents' => $subValue,
                     ];
                 }
diff --git a/tests/Functional/InlineFileTest.php b/tests/Functional/InlineFileTest.php
index 0942f27..91c9003 100644
--- a/tests/Functional/InlineFileTest.php
+++ b/tests/Functional/InlineFileTest.php
@@ -10,18 +10,13 @@ class InlineFileTest extends \PHPUnit_Framework_TestCase
 {
     public function testSimpleExample()
     {
-        // Create a Closure that validates the $files parameter to RestClient::send()
         $fileValidator = function($files) {
-            // Validate standard params
-            $this->assertContains(['name'=>'from',    'contents'=>'bob@example.com'], $files);
-            $this->assertContains(['name'=>'to',      'contents'=>'alice@example.com'], $files);
-            $this->assertContains(['name'=>'subject', 'contents'=>'Foo'], $files);
-            $this->assertContains(['name'=>'text',    'contents'=>'Bar'], $files);
-
             $fileNames = [
                 ['name'=>'inline[0]', 'filename'=>'foo.png'],
                 ['name'=>'inline[1]', 'filename'=>'bar.png']
             ];
+
+            // Make sure that both files exists
             foreach ($fileNames as $idx => $fileName) {
                 foreach ($files as $file) {
                     if ($file['name'] === $fileName['name'] && $file['filename'] === $fileName['filename']) {
diff --git a/tests/Functional/NoSamePostNameTest.php b/tests/Functional/NoSamePostNameTest.php
index 0f346ff..2e6678c 100644
--- a/tests/Functional/NoSamePostNameTest.php
+++ b/tests/Functional/NoSamePostNameTest.php
@@ -26,7 +26,16 @@ class NoSamePostNameTest extends \PHPUnit_Framework_TestCase
 
         $builder = $mailgun->MessageBuilder();
         $builder->setFromAddress("bob@example.com");
-        $builder->addToRecipient("alice@example.com");
+        $builder->addToRecipient("to1@example.com");
+        $builder->addToRecipient("to2@example.com");
+        $builder->addCcRecipient("cc1@example.com");
+        $builder->addCcRecipient("cc2@example.com");
+        $builder->addBccRecipient("bcc1@example.com");
+        $builder->addBccRecipient("bcc2@example.com");
+        $builder->addCustomParameter('foo', 'bar');
+        $builder->addCustomParameter('foo', 'baz');
+        $builder->addCampaignId('campaign0');
+        $builder->addCampaignId('campaign1');
         $builder->setSubject("Foo");
         $builder->setTextBody("Bar");