diff --git a/pandas/core/accessor.py b/pandas/core/accessor.py
index 96b7cf8f97c3f..963c9c65cb30c 100644
--- a/pandas/core/accessor.py
+++ b/pandas/core/accessor.py
@@ -58,7 +58,9 @@ def _delegate_method(self, name, *args, **kwargs):
         raise TypeError("You cannot call method {name}".format(name=name))
 
     @classmethod
-    def _add_delegate_accessors(cls, delegate, accessors, typ, overwrite=False):
+    def _add_delegate_accessors(
+        cls, delegate, accessors, typ: str, overwrite: bool = False
+    ):
         """
         Add accessors to cls from the delegate class.
 
@@ -107,7 +109,7 @@ def f(self, *args, **kwargs):
                 setattr(cls, name, f)
 
 
-def delegate_names(delegate, accessors, typ, overwrite=False):
+def delegate_names(delegate, accessors, typ: str, overwrite: bool = False):
     """
     Add delegated names to a class using a class decorator.  This provides
     an alternative usage to directly calling `_add_delegate_accessors`
@@ -162,7 +164,7 @@ class CachedAccessor:
         the single argument ``data``.
     """
 
-    def __init__(self, name, accessor):
+    def __init__(self, name: str, accessor) -> None:
         self._name = name
         self._accessor = accessor
 
diff --git a/pandas/core/sorting.py b/pandas/core/sorting.py
index b99ac9cc333c6..3005bdcbe78a4 100644
--- a/pandas/core/sorting.py
+++ b/pandas/core/sorting.py
@@ -187,7 +187,7 @@ def indexer_from_factorized(labels, shape, compress: bool = True):
     return get_group_index_sorter(ids, ngroups)
 
 
-def lexsort_indexer(keys, orders=None, na_position="last"):
+def lexsort_indexer(keys, orders=None, na_position: str = "last"):
     from pandas.core.arrays import Categorical
 
     labels = []
@@ -233,7 +233,9 @@ def lexsort_indexer(keys, orders=None, na_position="last"):
     return indexer_from_factorized(labels, shape)
 
 
-def nargsort(items, kind="quicksort", ascending: bool = True, na_position="last"):
+def nargsort(
+    items, kind: str = "quicksort", ascending: bool = True, na_position: str = "last"
+):
     """
     This is intended to be a drop-in replacement for np.argsort which
     handles NaNs. It adds ascending and na_position parameters.
@@ -273,7 +275,7 @@ class _KeyMapper:
     Ease my suffering. Map compressed group id -> key tuple
     """
 
-    def __init__(self, comp_ids, ngroups, levels, labels):
+    def __init__(self, comp_ids, ngroups: int, levels, labels):
         self.levels = levels
         self.labels = labels
         self.comp_ids = comp_ids.astype(np.int64)