diff --git a/jedi/api/completion.py b/jedi/api/completion.py
index 71e3e10c..35f62d2b 100644
--- a/jedi/api/completion.py
+++ b/jedi/api/completion.py
@@ -199,7 +199,7 @@ class Completion:
     def _trailer_completions(self, atom_expr):
         scopes = self._evaluator.eval_element(atom_expr)
         completion_names = []
-        debug.dbg('possible completion scopes: %s', scopes)
+        debug.dbg('trailer completion scopes: %s', scopes)
         for s in scopes:
             names = []
             for names_dict in s.names_dicts(search_global=False):
diff --git a/jedi/evaluate/compiled/mixed.py b/jedi/evaluate/compiled/mixed.py
index 24e4e731..ce657c38 100644
--- a/jedi/evaluate/compiled/mixed.py
+++ b/jedi/evaluate/compiled/mixed.py
@@ -31,11 +31,16 @@ class MixedObject(object):
         self._evaluator = evaluator
         self.obj = obj
         self.node_name = node_name
-        self._definition = node_name.get_definition()
+        self.definition = node_name.get_definition()
+
+    @property
+    def names_dict(self):
+        return LazyMixedNamesDict(self._evaluator, self, is_instance=False)
 
     def names_dicts(self, search_global):
+        # TODO is this needed?
         assert search_global is False
-        return [LazyMixedNamesDict(self._evaluator, self, is_instance=False)]
+        return [self.names_dict]
 
     def api_type(self):
         mappings = {
@@ -44,13 +49,13 @@ class MixedObject(object):
             'funcdef': 'function',
             'file_input': 'module',
         }
-        return mappings[self._definition.type]
+        return mappings[self.definition.type]
 
     def __repr__(self):
         return '<%s: %s>' % (type(self).__name__, repr(self.obj))
 
     def __getattr__(self, name):
-        return getattr(self._definition, name)
+        return getattr(self.definition, name)
 
 
 class MixedName(compiled.CompiledName):
diff --git a/jedi/evaluate/representation.py b/jedi/evaluate/representation.py
index 66d92463..7de3d6eb 100644
--- a/jedi/evaluate/representation.py
+++ b/jedi/evaluate/representation.py
@@ -46,6 +46,7 @@ from jedi import common
 from jedi.cache import underscore_memoization, cache_star_import
 from jedi.evaluate.cache import memoize_default, CachedMetaClass, NO_DEFAULT
 from jedi.evaluate import compiled
+from jedi.evaluate.compiled import mixed
 from jedi.evaluate import recursion
 from jedi.evaluate import iterable
 from jedi.evaluate import docstrings
@@ -631,13 +632,20 @@ class FunctionExecution(Executed):
     def __init__(self, evaluator, base, *args, **kwargs):
         super(FunctionExecution, self).__init__(evaluator, base, *args, **kwargs)
         self._copy_dict = {}
-        new_func = helpers.deep_ast_copy(base.base_func, new_elements=self._copy_dict)
-        for child in new_func.children:
+        funcdef = base.base_func
+        if isinstance(funcdef, mixed.MixedObject):
+            # The extra information in mixed is not needed anymore. We can just
+            # unpack it and give it the tree object.
+            funcdef = funcdef.definition
+
+        # Just overwrite the old version. We don't need it anymore.
+        funcdef = helpers.deep_ast_copy(funcdef, new_elements=self._copy_dict)
+        for child in funcdef.children:
             if child.type not in ('operator', 'keyword'):
                 # Not all nodes are properly copied by deep_ast_copy.
                 child.parent = self
-        self.children = new_func.children
-        self.names_dict = new_func.names_dict
+        self.children = funcdef.children
+        self.names_dict = funcdef.names_dict
 
     @memoize_default(default=set())
     @recursion.execution_recursion_decorator