diff --git a/README.md b/README.md
index d7d6f51..36fd22f 100644
--- a/README.md
+++ b/README.md
@@ -98,6 +98,8 @@ $attachment_content = $ticket_article->getAttachmentContent(23);
 
 In the above example 23 is the ID of the attachment. This ID can be found within the `attachments` array of the ticket article data. Usually you want to loop over this array to fetch the content of all attachments.
 
+`getAttachmentContent()` returns the attachment content as a string, ready to use.
+
 ### Updating Resource objects
 If you fetched a `Resource` object and changed some values, you have to send your changes to Zammad. You do this with a simple call:
 ```php
diff --git a/src/Resource/TicketArticle.php b/src/Resource/TicketArticle.php
index c36c71a..f14b2f6 100644
--- a/src/Resource/TicketArticle.php
+++ b/src/Resource/TicketArticle.php
@@ -117,6 +117,9 @@ public function getAttachmentContent($attachment_id)
         }
 
         $content = $response->getBody();
+        if ( $content instanceof \Psr\Http\Message\StreamInterface ) {
+            $content = $content->getContents();
+        }
         return $content;
     }
 }
diff --git a/test/ZammadAPIClient/Resource/TicketArticleTest.php b/test/ZammadAPIClient/Resource/TicketArticleTest.php
index f42b0f9..7eb4e3f 100644
--- a/test/ZammadAPIClient/Resource/TicketArticleTest.php
+++ b/test/ZammadAPIClient/Resource/TicketArticleTest.php
@@ -166,7 +166,7 @@ public function testCreate( $values, $expected_success )
 
                     // Fetch attachment content
                     $content = $object->getAttachmentContent( $attachment['id'] );
-                    $this->assertEquals(
+                    $this->assertSame(
                         $expected_content,
                         $content,
                         "Content of file $filename must match expected one."