diff --git a/sanic/asgi.py b/sanic/asgi.py
index e9bcf2de..9e5e5e65 100644
--- a/sanic/asgi.py
+++ b/sanic/asgi.py
@@ -5,8 +5,7 @@ from inspect import isawaitable
 from typing import Any, Awaitable, Callable, MutableMapping, Union
 from urllib.parse import quote
 
-from multidict import CIMultiDict
-
+from sanic.compat import Header
 from sanic.exceptions import InvalidUsage, ServerError
 from sanic.log import logger
 from sanic.request import Request
@@ -186,7 +185,7 @@ class ASGIApp:
         instance.transport.add_task = sanic_app.loop.create_task
         instance.transport.loop = sanic_app.loop
 
-        headers = CIMultiDict(
+        headers = Header(
             [
                 (key.decode("latin-1"), value.decode("latin-1"))
                 for key, value in scope.get("headers", [])
diff --git a/sanic/compat.py b/sanic/compat.py
index 30aec0a7..6ca7e344 100644
--- a/sanic/compat.py
+++ b/sanic/compat.py
@@ -2,6 +2,5 @@ from multidict import CIMultiDict
 
 
 class Header(CIMultiDict):
-
-	def get_all(self, key):
-		return self.getall(key, [])
+    def get_all(self, key):
+        return self.getall(key, default=[])
diff --git a/sanic/response.py b/sanic/response.py
index 34f59e66..6f937c95 100644
--- a/sanic/response.py
+++ b/sanic/response.py
@@ -4,8 +4,8 @@ from os import path
 from urllib.parse import quote_plus
 
 from aiofiles import open as open_async
-from multidict import CIMultiDict
 
+from sanic.compat import Header
 from sanic.cookies import CookieJar
 from sanic.helpers import STATUS_CODES, has_message_body, remove_entity_headers
 
@@ -74,7 +74,7 @@ class StreamingHTTPResponse(BaseHTTPResponse):
         self.content_type = content_type
         self.streaming_fn = streaming_fn
         self.status = status
-        self.headers = CIMultiDict(headers or {})
+        self.headers = Header(headers or {})
         self.chunked = chunked
         self._cookies = None
 
@@ -164,7 +164,7 @@ class HTTPResponse(BaseHTTPResponse):
             self.body = body_bytes
 
         self.status = status
-        self.headers = CIMultiDict(headers or {})
+        self.headers = Header(headers or {})
         self._cookies = None
 
     def output(self, version="1.1", keep_alive=False, keep_alive_timeout=None):