diff --git a/muk_web_preview_attachment/tests/test_attachment_extension.py b/muk_web_preview_attachment/tests/test_attachment_extension.py
index 3c05acd..ca7411a 100644
--- a/muk_web_preview_attachment/tests/test_attachment_extension.py
+++ b/muk_web_preview_attachment/tests/test_attachment_extension.py
@@ -51,10 +51,11 @@ class AttachmentExtensionTestCase(common.TransactionCase):
             })
         self.assertEqual(self.sample.extension, ".png")
         
-    def test_attachment_extension_bianry(self):
+    def test_attachment_extension_mimetype(self):
         with closing(open(os.path.join(_path, 'tests/data/sample.png'), 'r')) as file:
             self.sample = self.attachment_model.create({
                 'name': "test",
+                'mimetype': "image/png",
                 'datas': base64.encodestring(file.read()),
             })
         self.assertEqual(self.sample.extension, ".png")