diff --git a/setup.cfg b/setup.cfg
index 5cda9035e..c9ff3d363 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -71,6 +71,7 @@ pytest-parametrize-values-row-type = tuple
 profile = black
 
 [mypy]
+disallow_untyped_defs = true
 disallow_any_generics = true
 disallow_incomplete_defs = true
 disallow_subclassing_any = true
@@ -84,3 +85,6 @@ warn_redundant_casts = true
 warn_return_any = true
 warn_unused_configs = true
 warn_unused_ignores = true
+
+[mypy-tests.*]
+disallow_untyped_defs = false