diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 79ad1ee94..171a3e7b0 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -2270,8 +2270,8 @@ class SlotsAttributeDocumenter(AttributeDocumenter):
                           % self.__class__.__name__,
                           RemovedInSphinx50Warning, stacklevel=2)
         name = self.objpath[-1]
-        __slots__ = safe_getattr(self.parent, '__slots__', [])
-        if isinstance(__slots__, dict) and isinstance(__slots__.get(name), str):
+        __slots__ = inspect.getslots(self.parent)
+        if __slots__ and isinstance(__slots__.get(name, None), str):
             docstring = prepare_docstring(__slots__[name])
             return [docstring]
         else:
diff --git a/sphinx/ext/autodoc/importer.py b/sphinx/ext/autodoc/importer.py
index 29c56c54b..adfa6d05d 100644
--- a/sphinx/ext/autodoc/importer.py
+++ b/sphinx/ext/autodoc/importer.py
@@ -16,7 +16,7 @@ from typing import Any, Callable, Dict, List, Mapping, NamedTuple, Optional, Tup
 from sphinx.deprecation import RemovedInSphinx40Warning, deprecated_alias
 from sphinx.pycode import ModuleAnalyzer
 from sphinx.util import logging
-from sphinx.util.inspect import isclass, isenumclass, safe_getattr
+from sphinx.util.inspect import getslots, isclass, isenumclass, safe_getattr
 
 if False:
     # For type annotation
@@ -203,14 +203,15 @@ def get_object_members(subject: Any, objpath: List[str], attrgetter: Callable,
                 members[name] = Attribute(name, True, value)
 
     # members in __slots__
-    if isclass(subject) and getattr(subject, '__slots__', None) is not None:
-        from sphinx.ext.autodoc import SLOTSATTR
+    try:
+        __slots__ = getslots(subject)
+        if __slots__:
+            from sphinx.ext.autodoc import SLOTSATTR
 
-        slots = subject.__slots__
-        if isinstance(slots, str):
-            slots = [slots]
-        for name in slots:
-            members[name] = Attribute(name, True, SLOTSATTR)
+            for name in __slots__:
+                members[name] = Attribute(name, True, SLOTSATTR)
+    except (TypeError, ValueError):
+        pass
 
     # other members
     for name in dir(subject):