diff --git a/rest_framework_docs/api_endpoint.py b/rest_framework_docs/api_endpoint.py
index 953f9a0..629d4d8 100644
--- a/rest_framework_docs/api_endpoint.py
+++ b/rest_framework_docs/api_endpoint.py
@@ -89,7 +89,8 @@ def __get_docstring__(self):
 
     def __get_permissions_class__(self):
         for perm_class in self.pattern.callback.cls.permission_classes:
-            return perm_class.__name__
+            if inspect.isclass(perm_class):
+                return perm_class.__name__
 
     def __get_serializer__(self):
         try: