diff --git a/mypy.ini b/mypy.ini
deleted file mode 100644
index 685c02599..000000000
--- a/mypy.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[mypy]
-disallow_untyped_defs = True
-check_untyped_defs = True
diff --git a/pyproject.toml b/pyproject.toml
index a0a3d30be..d100c75ac 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -66,3 +66,8 @@ profile = "attrs"
         directory = "change"
         name = "Changes"
         showcontent = true
+
+
+[tool.mypy]
+disallow_untyped_defs = true
+check_untyped_defs = true
diff --git a/setup.py b/setup.py
index f96894440..392bc04de 100644
--- a/setup.py
+++ b/setup.py
@@ -62,7 +62,7 @@
     and platform.python_implementation() != "PyPy"
 ):
     EXTRAS_REQUIRE["tests_no_zope"].extend(
-        ["mypy!=0.940", "pytest-mypy-plugins"]
+        ["mypy>=0.900,!=0.940", "pytest-mypy-plugins"]
     )
 
 EXTRAS_REQUIRE["tests"] = EXTRAS_REQUIRE["tests_no_zope"] + ["zope.interface"]