diff --git a/jedi/evaluate/context/function.py b/jedi/evaluate/context/function.py
index c48ab5fc..a982abc4 100644
--- a/jedi/evaluate/context/function.py
+++ b/jedi/evaluate/context/function.py
@@ -38,7 +38,7 @@ class LambdaName(AbstractNameDefinition):
         return ContextSet([self._lambda_context])
 
 
-class FunctionAndClassMixin(object):
+class FunctionAndClassBase(TreeContext):
     def get_qualified_names(self):
         if self.parent_context.is_class():
             n = self.parent_context.get_qualified_names()
@@ -51,11 +51,8 @@ class FunctionAndClassMixin(object):
         else:
             return None
 
-    def py__name__(self):
-        return self.name.string_name
 
-
-class FunctionMixin(FunctionAndClassMixin):
+class FunctionMixin(object):
     api_type = u'function'
 
     def get_filters(self, search_global=False, until_position=None, origin_scope=None):
@@ -89,6 +86,9 @@ class FunctionMixin(FunctionAndClassMixin):
             return LambdaName(self)
         return ContextName(self, self.tree_node.name)
 
+    def py__name__(self):
+        return self.name.string_name
+
     def py__call__(self, arguments):
         function_execution = self.get_function_execution(arguments)
         return function_execution.infer()
@@ -100,7 +100,7 @@ class FunctionMixin(FunctionAndClassMixin):
         return FunctionExecutionContext(self.evaluator, self.parent_context, self, arguments)
 
 
-class FunctionContext(use_metaclass(CachedMetaClass, FunctionMixin, TreeContext)):
+class FunctionContext(use_metaclass(CachedMetaClass, FunctionMixin, FunctionAndClassBase)):
     """
     Needed because of decorators. Decorators are evaluated here.
     """
diff --git a/jedi/evaluate/context/klass.py b/jedi/evaluate/context/klass.py
index 65383d3c..8d0e08c2 100644
--- a/jedi/evaluate/context/klass.py
+++ b/jedi/evaluate/context/klass.py
@@ -47,8 +47,8 @@ from jedi.evaluate.filters import ParserTreeFilter
 from jedi.evaluate.names import TreeNameDefinition, ContextName
 from jedi.evaluate.arguments import unpack_arglist
 from jedi.evaluate.base_context import ContextSet, iterator_to_context_set, \
-    TreeContext, NO_CONTEXTS
-from jedi.evaluate.context.function import FunctionAndClassMixin
+    NO_CONTEXTS
+from jedi.evaluate.context.function import FunctionAndClassBase
 
 
 def apply_py__get__(context, instance, class_context):
@@ -118,7 +118,7 @@ class ClassFilter(ParserTreeFilter):
         return [name for name in names if self._access_possible(name)]
 
 
-class ClassMixin(FunctionAndClassMixin):
+class ClassMixin(object):
     def is_class(self):
         return True
 
@@ -133,6 +133,9 @@ class ClassMixin(FunctionAndClassMixin):
     def name(self):
         return ContextName(self, self.tree_node.name)
 
+    def py__name__(self):
+        return self.name.string_name
+
     def get_param_names(self):
         for context_ in self.py__getattribute__(u'__init__'):
             if context_.is_function():
@@ -199,7 +202,7 @@ class ClassMixin(FunctionAndClassMixin):
                 yield next(type_.get_filters())
 
 
-class ClassContext(use_metaclass(CachedMetaClass, ClassMixin, TreeContext)):
+class ClassContext(use_metaclass(CachedMetaClass, ClassMixin, FunctionAndClassBase)):
     """
     This class is not only important to extend `tree.Class`, it is also a
     important for descriptors (if the descriptor methods are evaluated or not).
diff --git a/test/test_evaluate/test_signature.py b/test/test_evaluate/test_signature.py
index 2c8083f6..32f36dd9 100644
--- a/test/test_evaluate/test_signature.py
+++ b/test/test_evaluate/test_signature.py
@@ -13,11 +13,17 @@ from jedi.evaluate.gradual.conversion import stub_to_actual_context_set
 
         ('pow', 'pow(x, y, z=None) -> number', ['x', 'y', 'z'], lt, (3, 5)),
         ('pow', 'pow(x, y, z=None, /)', ['x', 'y', 'z'], ge, (3, 5)),
+
+        ('bytes.partition', 'partition(self, sep) -> (head, sep, tail)', ['self', 'sep'], lt, (3, 5)),
+        ('bytes.partition', 'partition(self, sep, /)', ['self', 'sep'], ge, (3, 5)),
+
+        ('bytes().partition', 'partition(sep) -> (head, sep, tail)', ['sep'], lt, (3, 5)),
+        ('bytes().partition', 'partition(sep, /)', ['sep'], ge, (3, 5)),
     ]
 )
 def test_compiled_signature(Script, environment, code, sig, names, op, version):
     if not op(environment.version_info, version):
-        pytest.skip("Not running for this version")
+        return  # The test right next to it should take over.
 
     d, = Script(code).goto_definitions()
     context, = d._name.infer()