diff --git a/jedi/evaluate/base_context.py b/jedi/evaluate/base_context.py
index cec5182b..daba9639 100644
--- a/jedi/evaluate/base_context.py
+++ b/jedi/evaluate/base_context.py
@@ -280,7 +280,6 @@ class ContextualizedName(ContextualizedNode):
 
 
 def _getitem(context, index_contexts, contextualized_node):
-    from jedi.evaluate.compiled import CompiledObject
     from jedi.evaluate.context.iterable import Slice
 
     # The actual getitem call.
diff --git a/jedi/evaluate/context/instance.py b/jedi/evaluate/context/instance.py
index a82c3dbb..e9e90c55 100644
--- a/jedi/evaluate/context/instance.py
+++ b/jedi/evaluate/context/instance.py
@@ -225,15 +225,6 @@ class AbstractInstanceContext(Context):
 class CompiledInstance(AbstractInstanceContext):
     def __init__(self, evaluator, parent_context, class_context, var_args):
         self._original_var_args = var_args
-
-        # I don't think that dynamic append lookups should happen here. That
-        # sounds more like something that should go to py__iter__.
-        if class_context.py__name__() in ['list', 'set'] \
-                and parent_context.get_root_context() == evaluator.builtins_module:
-            # compare the module path with the builtin name.
-            if settings.dynamic_array_additions:
-                var_args = iterable.get_dynamic_array_instance(self, var_args)
-
         super(CompiledInstance, self).__init__(evaluator, parent_context, class_context, var_args)
 
     @property
@@ -256,6 +247,14 @@ class CompiledInstance(AbstractInstanceContext):
 
 class TreeInstance(AbstractInstanceContext):
     def __init__(self, evaluator, parent_context, class_context, var_args):
+        # I don't think that dynamic append lookups should happen here. That
+        # sounds more like something that should go to py__iter__.
+        if class_context.py__name__() in ['list', 'set'] \
+                and parent_context.get_root_context() == evaluator.builtins_module:
+            # compare the module path with the builtin name.
+            if settings.dynamic_array_additions:
+                var_args = iterable.get_dynamic_array_instance(self, var_args)
+
         super(TreeInstance, self).__init__(evaluator, parent_context,
                                            class_context, var_args)
         self.tree_node = class_context.tree_node
diff --git a/jedi/evaluate/context/iterable.py b/jedi/evaluate/context/iterable.py
index 6b53ae6c..9ec5723c 100644
--- a/jedi/evaluate/context/iterable.py
+++ b/jedi/evaluate/context/iterable.py
@@ -38,7 +38,7 @@ from jedi.evaluate.helpers import execute_evaluated
 from jedi.evaluate.filters import ParserTreeFilter, BuiltinOverwrite, \
     publish_method
 from jedi.evaluate.base_context import ContextSet, NO_CONTEXTS, \
-    TreeContext, ContextualizedNode, iterate_contexts
+    TreeContext, ContextualizedNode, iterate_contexts, HelperContextMixin
 from jedi.parser_utils import get_comp_fors
 
 
@@ -637,8 +637,8 @@ def _check_array_additions(context, sequence):
         if add_name in ['insert']:
             params = params[1:]
         if add_name in ['append', 'add', 'insert']:
-            for key, whatever in params:
-                result.add(whatever)
+            for key, lazy_context in params:
+                result.add(lazy_context)
         elif add_name in ['extend', 'update']:
             for key, lazy_context in params:
                 result |= set(lazy_context.infer().iterate())
@@ -704,7 +704,7 @@ def get_dynamic_array_instance(instance, arguments):
     return arguments.ValuesArguments([ContextSet([ai])])
 
 
-class _ArrayInstance(object):
+class _ArrayInstance(HelperContextMixin):
     """
     Used for the usage of set() and list().
     This is definitely a hack, but a good one :-)
@@ -714,6 +714,10 @@ class _ArrayInstance(object):
         self.instance = instance
         self.var_args = var_args
 
+    def py__class__(self):
+        tuple_, = self.instance.evaluator.builtins_module.py__getattribute__('tuple')
+        return tuple_
+
     def py__iter__(self):
         var_args = self.var_args
         try:
diff --git a/jedi/third_party/typeshed b/jedi/third_party/typeshed
index 0bde5c8a..cd1fbb0e 160000
--- a/jedi/third_party/typeshed
+++ b/jedi/third_party/typeshed
@@ -1 +1 @@
-Subproject commit 0bde5c8aee39e2aca11673d9c07da2ae6c6ad108
+Subproject commit cd1fbb0e9fa5a0cc1ac5d1907434257b01082b86
diff --git a/test/completion/dynamic_arrays.py b/test/completion/dynamic_arrays.py
index 5cb52fc6..0f03c8fd 100644
--- a/test/completion/dynamic_arrays.py
+++ b/test/completion/dynamic_arrays.py
@@ -55,9 +55,10 @@ list(arr)[10]
 arr = [1.0]
 arr.extend([1,2,3])
 arr.extend([])
-arr.extend("")  # should ignore
+arr.extend("")
+arr.extend(list)  # should ignore
 
-#? float() int()
+#? float() int() str()
 arr[100]
 
 a = set(arr)
@@ -94,7 +95,7 @@ arr2[0]
 lst = [1]
 lst.append(1.0)
 s = set(lst)
-s.add("")
+s.add("ahh")
 lst = list(s)
 lst.append({})