diff --git a/tests/requirements-py3.txt b/tests/requirements-py3.txt
index c2b16bec6..7abb66b9c 100644
--- a/tests/requirements-py3.txt
+++ b/tests/requirements-py3.txt
@@ -1,7 +1,7 @@
 # Tests requirements
 jmespath
 mitmproxy; python_version >= '3.6'
-mitmproxy==3.0.4; python_version < '3.6'
+mitmproxy<4.0.0; python_version < '3.6'
 pytest
 pytest-cov
 pytest-twisted