diff --git a/sanic/response.py b/sanic/response.py
index 2402b432..7a490ffe 100644
--- a/sanic/response.py
+++ b/sanic/response.py
@@ -195,8 +195,12 @@ class HTTPResponse(BaseHTTPResponse):
         timeout_header = b''
         if keep_alive and keep_alive_timeout is not None:
             timeout_header = b'Keep-Alive: %d\r\n' % keep_alive_timeout
-        self.headers['Content-Length'] = self.headers.get(
-            'Content-Length', len(self.body))
+
+        content_length = 0
+        if self.status is not 204:
+            content_length = self.headers.get('Content-Length', len(self.body))
+        self.headers['Content-Length'] = content_length
+
         self.headers['Content-Type'] = self.headers.get(
             'Content-Type', self.content_type)
 
@@ -218,7 +222,7 @@ class HTTPResponse(BaseHTTPResponse):
                    b'keep-alive' if keep_alive else b'close',
                    timeout_header,
                    headers,
-                   self.body
+                   self.body if self.status is not 204 else b''
                )
 
     @property
@@ -239,8 +243,7 @@ def json(body, status=200, headers=None,
     :param headers: Custom Headers.
     :param kwargs: Remaining arguments that are passed to the json encoder.
     """
-    _body = dumps(body, **kwargs) if body else None
-    return HTTPResponse(_body, headers=headers,
+    return HTTPResponse(dumps(body, **kwargs), headers=headers,
                         status=status, content_type=content_type)
 
 
diff --git a/tests/test_requests.py b/tests/test_requests.py
index 49e73a55..14da4b0b 100644
--- a/tests/test_requests.py
+++ b/tests/test_requests.py
@@ -104,6 +104,7 @@ def test_json():
 
     assert results.get('test') == True
 
+
 def test_empty_json():
     app = Sanic('test_json')
 
@@ -114,7 +115,7 @@ def test_empty_json():
 
     request, response = app.test_client.get('/')
     assert response.status == 200
-    assert response.text == ''
+    assert response.text == 'null'
 
 
 def test_invalid_json():
diff --git a/tests/test_response.py b/tests/test_response.py
index 88bd8a3a..475da8b6 100644
--- a/tests/test_response.py
+++ b/tests/test_response.py
@@ -43,7 +43,7 @@ def test_method_not_allowed():
         return response.json({'hello': 'world'})
 
     request, response = app.test_client.head('/')
-    assert response.headers['Allow']== 'GET'
+    assert response.headers['Allow'] == 'GET'
 
     @app.post('/')
     async def test(request):