diff --git a/gunicorn/http/message.py b/gunicorn/http/message.py
index fe7394f8..0c8f4954 100644
--- a/gunicorn/http/message.py
+++ b/gunicorn/http/message.py
@@ -173,9 +173,9 @@ class Request(Message):
         else:
             self.host = self.host.rsplit(":", 1)[0]
             self.port = parts.port
-        self.path = parts.path or None
-        self.query = parts.query or None
-        self.fragment = parts.fragment or None
+        self.path = parts.path or ""
+        self.query = parts.query or ""
+        self.fragment = parts.fragment or ""
 
         # Version
         match = self.versre.match(bits[2])
diff --git a/gunicorn/http/wsgi.py b/gunicorn/http/wsgi.py
index c954720f..63054597 100644
--- a/gunicorn/http/wsgi.py
+++ b/gunicorn/http/wsgi.py
@@ -93,7 +93,7 @@ def create(req, sock, client, server, debug=False):
         "SERVER_SOFTWARE": SERVER_VERSION,
         "REQUEST_METHOD": req.method,
         "PATH_INFO": unquote(path_info),
-        "QUERY_STRING": req.query or '',
+        "QUERY_STRING": req.query,
         "RAW_URI": req.path,
         "CONTENT_TYPE": content_type,
         "CONTENT_LENGTH": content_length,