diff --git a/src/milla/tests/test_app.py b/src/milla/tests/test_app.py
index 15a72d0..3238cff 100644
--- a/src/milla/tests/test_app.py
+++ b/src/milla/tests/test_app.py
@@ -33,7 +33,7 @@ class ResponseMaker(object):
     def __init__(self, http_version=1.1):
         self.http_version = http_version
         self.headers = ''
-        self.body = ''
+        self.body = b''
 
     def start_response(self, status, response_headers):
         self.headers += 'HTTP/{0} {1}\r\n'.format(self.http_version, status)
@@ -78,7 +78,7 @@ def test_favicon():
     app_iter = app(environ, response.start_response)
     response.finish_response(app_iter)
     assert response.headers.startswith('HTTP/1.1 200'), response.headers
-    assert response.body.startswith('\x00\x00\x01\x00'), response.body
+    assert response.body.startswith(b'\x00\x00\x01\x00'), response.body
 
 def test_allow_header_disallowed():
     '''HTTP 405 is returned for disallowed HTTP request methods
@@ -138,7 +138,7 @@ def test_emulated_method():
     })
     body = environ['wsgi.input']
     body.seek(0)
-    body.write('_method=PUT')
+    body.write(b'_method=PUT')
     body.seek(0)
     response = ResponseMaker()
     app_iter = app(environ, response.start_response)
@@ -358,7 +358,7 @@ def test_httperror_response():
     '''
 
     def controller(request):
-        raise webob.exc.HTTPClientError()
+        raise webob.exc.HTTPClientError('NotFound')
 
     app = milla.app.Application(StubResolver(controller))
     environ = testing_environ()
@@ -366,7 +366,7 @@ def test_httperror_response():
     app_iter = app(environ, response.start_response)
     response.finish_response(app_iter)
     assert response.headers.startswith('HTTP/1.1 400'), response.headers
-    assert webob.exc.HTTPClientError.explanation in response.body, response.body
+    assert b'NotFound' in response.body, response.body
 
 def test_single_start_response():
     '''Ensure start_response is only called once'''
@@ -393,4 +393,4 @@ def test_single_start_response():
     response.finish_response(app_iter)
     assert start_response.call_count == 1, start_response.call_count
     assert response.headers.startswith('HTTP/1.1 200 OK'), response.headers
-    assert response.body == 'test', response.body
+    assert response.body == b'test', response.body