diff --git a/azure/functions/_http.py b/azure/functions/_http.py
index 9cae82d7..49faea60 100644
--- a/azure/functions/_http.py
+++ b/azure/functions/_http.py
@@ -8,10 +8,10 @@
 import types
 import typing
 
-from multidict._multidict import MultiDict
+import werkzeug.datastructures
 from werkzeug import formparser as _wk_parser
 from werkzeug import http as _wk_http
-from werkzeug.datastructures import Headers, FileStorage
+from werkzeug.datastructures import Headers, FileStorage, MultiDict
 
 from . import _abc
 
@@ -175,8 +175,8 @@ def __init__(self,
         self.__route_params = types.MappingProxyType(route_params or {})
         self.__body_bytes = body
         self.__form_parsed = False
-        self.__form: MultiDict[str, str] = None
-        self.__files:MultiDict[str, FileStorage] = None
+        self.__form: MultiDict[str, str]
+        self.__files: MultiDict[str, FileStorage]
 
     @property
     def url(self):
@@ -231,7 +231,8 @@ def _parse_form_data(self):
         content_length = len(body)
         mimetype, options = _wk_http.parse_options_header(content_type)
         parser = _wk_parser.FormDataParser(
-            _wk_parser.default_stream_factory
+            _wk_parser.default_stream_factory, None, None,
+            werkzeug.datastructures.ImmutableMultiDict
         )
 
         body_stream = io.BytesIO(body)
diff --git a/setup.py b/setup.py
index 43d96c05..1e3af5b1 100644
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,12 @@
 from setuptools import find_packages, setup
 from azure.functions import __version__
 
-INSTALL_REQUIRES = ["werkzeug"]
+if sys.version_info[:2] >= (3, 9):
+    INSTALL_REQUIRES = ["werkzeug~=3.1.3"]
+elif sys.version_info[:2] == (3, 8):
+    INSTALL_REQUIRES = ["werkzeug~=3.0.6"]
+else:
+    INSTALL_REQUIRES = ["werkzeug"]
 
 EXTRA_REQUIRES = {
     'dev': [