diff --git a/jedi/inference/filters.py b/jedi/inference/filters.py
index 35692169..05a9efcf 100644
--- a/jedi/inference/filters.py
+++ b/jedi/inference/filters.py
@@ -3,7 +3,7 @@ Filters are objects that you can use to filter names in different scopes. They
 are needed for name resolution.
 """
 from abc import abstractmethod
-from typing import List, MutableMapping
+from typing import List, Optional, MutableMapping, Type
 import weakref
 
 from parso.tree import search_ancestor
@@ -15,7 +15,7 @@ from jedi.inference.base_value import ValueSet, ValueWrapper, \
 from jedi.parser_utils import get_cached_parent_scope
 from jedi.inference.utils import to_list
 from jedi.inference.names import TreeNameDefinition, ParamName, \
-    AnonymousParamName, AbstractNameDefinition
+    AnonymousParamName, AbstractNameDefinition, NameWrapper
 
 _definition_name_cache: MutableMapping[UsedNamesMapping, List[Name]]
 _definition_name_cache = weakref.WeakKeyDictionary()
@@ -39,7 +39,7 @@ class AbstractFilter(object):
 
 
 class FilterWrapper(object):
-    name_wrapper_class = None
+    name_wrapper_class: Optional[Type[NameWrapper]] = None
 
     def __init__(self, wrapped_filter):
         self._wrapped_filter = wrapped_filter
diff --git a/jedi/inference/names.py b/jedi/inference/names.py
index 81161359..1d20ba5f 100644
--- a/jedi/inference/names.py
+++ b/jedi/inference/names.py
@@ -1,5 +1,6 @@
 from abc import abstractmethod
 from inspect import Parameter
+from typing import Optional, Tuple
 
 from parso.tree import search_ancestor
 
@@ -24,8 +25,8 @@ def _merge_name_docs(names):
 
 
 class AbstractNameDefinition(object):
-    start_pos = None
-    string_name = None
+    start_pos: Optional[Tuple[int, int]] = None
+    string_name: Optional[str] = None
     parent_context = None
     tree_name = None
     is_value_name = True
diff --git a/jedi/inference/value/module.py b/jedi/inference/value/module.py
index 7ab4c298..b996d814 100644
--- a/jedi/inference/value/module.py
+++ b/jedi/inference/value/module.py
@@ -1,5 +1,6 @@
 import os
 from pathlib import Path
+from typing import Optional
 
 from jedi.inference.cache import inference_state_method_cache
 from jedi.inference.names import AbstractNameDefinition, ModuleName
@@ -145,7 +146,7 @@ class ModuleValue(ModuleMixin, TreeValue):
         )
         self.file_io = file_io
         if file_io is None:
-            self._path = None
+            self._path: Optional[Path] = None
         else:
             self._path = Path(file_io.path)
         self.string_names = string_names  # Optional[Tuple[str, ...]]