diff --git a/setup.py b/setup.py
index 441a1d8f9..7cbfb7ace 100644
--- a/setup.py
+++ b/setup.py
@@ -90,7 +90,7 @@ setup(
         'dev': [
             "flake8>=3.2.1, <3.4",
             "Flask>=0.10.1, <0.13",
-            "mypy>=0.501, <0.521",
+            "mypy>=0.520, <0.521",
             "pytest-cov>=2.2.1, <3",
             "pytest-faulthandler>=1.3.0, <2",
             "pytest-timeout>=1.0.0, <2",