diff --git a/docs/source/conf.py b/docs/source/conf.py
index d42134a1fa..abe3e608c6 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -28,7 +28,7 @@
 PATH_ROOT = os.path.join(PATH_HERE, '..', '..')
 sys.path.insert(0, os.path.abspath(PATH_ROOT))
 
-builtins.__LIGHTNING_BOLT_SETUP__ = True
+builtins.__LIGHTNING_BOLT_SETUP__: bool = True
 
 SPHINX_MOCK_REQUIREMENTS = int(os.environ.get('SPHINX_MOCK_REQUIREMENTS', True))
 
diff --git a/pl_bolts/__init__.py b/pl_bolts/__init__.py
index 40e4c0e6f3..b5656553d3 100644
--- a/pl_bolts/__init__.py
+++ b/pl_bolts/__init__.py
@@ -33,9 +33,9 @@
 try:
     # This variable is injected in the __builtins__ by the build process.
     # It used to enable importing subpackages when the binaries are not built.
-    __LIGHTNING_BOLT_SETUP__
+    _ = None if __LIGHTNING_BOLT_SETUP__ else None
 except NameError:
-    __LIGHTNING_BOLT_SETUP__ = False
+    __LIGHTNING_BOLT_SETUP__: bool = False
 
 if __LIGHTNING_BOLT_SETUP__:
     import sys  # pragma: no-cover
diff --git a/setup.cfg b/setup.cfg
index 7e5b819628..1661aad951 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -70,9 +70,6 @@ files = pl_bolts, tests
 disallow_untyped_defs = True
 ignore_missing_imports = True
 
-[mypy-pl_bolts.*]
-ignore_errors = True
-
 [mypy-pl_bolts.callbacks.*]
 ignore_errors = True
 
diff --git a/setup.py b/setup.py
index bf84b4102c..1c14816e7d 100755
--- a/setup.py
+++ b/setup.py
@@ -14,7 +14,7 @@
 # http://blog.ionelmc.ro/2014/05/25/python-packaging/
 
 PATH_ROOT = os.path.dirname(__file__)
-builtins.__LIGHTNING_BOLT_SETUP__ = True
+builtins.__LIGHTNING_BOLT_SETUP__: bool = True
 
 import pl_bolts  # noqa: E402