From ee835bf756685636b116c1ca76e1e8cce7432a2f Mon Sep 17 00:00:00 2001
From: Dusko Simidzija <dusko.simidzija@gmail.com>
Date: Wed, 19 Aug 2020 02:14:39 +0200
Subject: [PATCH] fix field order breaking on py35/36

---
 src/marshmallow/schema.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/marshmallow/schema.py b/src/marshmallow/schema.py
index 9549e4673..26f00a480 100644
--- a/src/marshmallow/schema.py
+++ b/src/marshmallow/schema.py
@@ -397,7 +397,9 @@ def __init__(
         self.fields = {}  # type: typing.Dict[str, ma_fields.Field]
         self.load_fields = {}  # type: typing.Dict[str, ma_fields.Field]
         self.dump_fields = {}  # type: typing.Dict[str, ma_fields.Field]
-        self.dump_serializers = {}  # type: typing.Dict[str, typing.Callable]
+        self.dump_serializers = (
+            self.dict_class()
+        )  # type: typing.Dict[str, typing.Callable]
         self._init_fields()
         messages = {}
         messages.update(self._default_error_messages)
@@ -1043,7 +1045,7 @@ def _init_fields(self) -> None:
         self.fields = fields_dict
         self.dump_fields = dump_fields
         self.load_fields = load_fields
-        self.dump_serializers = {}
+        self.dump_serializers = self.dict_class()
 
     def on_bind_field(self, field_name: str, field_obj: ma_fields.Field) -> None:
         """Hook to modify a field when it is bound to the `Schema`.