diff --git a/setup.cfg b/setup.cfg
index f7ff0888..3f0d76b0 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -29,6 +29,7 @@ install_requires =
     strict_rfc3339
     isodate
     attrs
+    werkzeug
     backports.functools-lru-cache; python_version<"3.0"
     backports.functools-partialmethod; python_version<"3.0"
 tests_require =
@@ -45,7 +46,7 @@ exclude =
 
 [options.extras_require]
 django = django>=2.2; python_version>="3.0"
-flask = werkzeug
+flask = flask
 
 [tool:pytest]
 addopts = -sv --flake8 --junitxml reports/junit.xml --cov openapi_core --cov-report term-missing --cov-report xml:reports/coverage.xml