fix tests

3 files changed, 3 insertions, 3 deletions

diff --git a/netlib/http/headers.py b/netlib/http/headers.py
index 2caf8d51..6067ff5e 100644
--- a/netlib/http/headers.py
+++ b/netlib/http/headers.py
@@ -76,7 +76,7 @@ class Headers(MultiDict):
         For use with the "Set-Cookie" header, see :py:meth:`get_all`.
     """
 
-    def __init__(self, fields=None, **headers):
+    def __init__(self, fields=(), **headers):
         """
         Args:
             fields: (optional) list of ``(name, value)`` header byte tuples,
diff --git a/netlib/http/request.py b/netlib/http/request.py
index 5a528bf2..a6e2a5ef 100644
--- a/netlib/http/request.py
+++ b/netlib/http/request.py
@@ -19,7 +19,7 @@ host_header_re = re.compile(r"^(?P<host>[^:]+|\[.+\])(?::(?P<port>\d+))?$")
 
 
 class RequestData(MessageData):
-    def __init__(self, first_line_format, method, scheme, host, port, path, http_version, headers=None, content=None,
+    def __init__(self, first_line_format, method, scheme, host, port, path, http_version, headers=(), content=None,
                  timestamp_start=None, timestamp_end=None):
         if not isinstance(headers, Headers):
             headers = Headers(headers)
diff --git a/netlib/http/response.py b/netlib/http/response.py
index 7d272e10..a6a5bf47 100644
--- a/netlib/http/response.py
+++ b/netlib/http/response.py
@@ -11,7 +11,7 @@ from .. import utils
 
 
 class ResponseData(MessageData):
-    def __init__(self, http_version, status_code, reason=None, headers=None, content=None,
+    def __init__(self, http_version, status_code, reason=None, headers=(), content=None,
                  timestamp_start=None, timestamp_end=None):
         if not isinstance(headers, Headers):
             headers = Headers(headers)