diff --git a/beniget/beniget.py b/beniget/beniget.py
index fe38b13..efe40bb 100644
--- a/beniget/beniget.py
+++ b/beniget/beniget.py
@@ -1058,6 +1058,7 @@ class DefUseChains(ast.NodeVisitor):
             dnode = self.chains.setdefault(node, Def(node))
             for default in node.args.defaults:
                 self.visit(default).add_user(dnode)
+            # a lambda never has kw_defaults
             self._defered.append((node,
                                   list(self._definitions),
                                   list(self._scopes),
@@ -1067,7 +1068,7 @@ class DefUseChains(ast.NodeVisitor):
         elif step is DefinitionStep:
             dnode = self.chains[node]
             with self.ScopeContext(node):
-                for a in node.args.args:
+                for a in _iter_arguments(node.args):
                     self.visit(a)
                 self.visit(node.body).add_user(dnode)
             return dnode

diff --git a/tests/test_chains.py b/tests/test_chains.py
index d2fa72c..ff309e7 100644
--- a/tests/test_chains.py
+++ b/tests/test_chains.py
@@ -357,6 +357,14 @@ while done:
             'x -> (x -> (Tuple -> (Lambda -> ())))',
         ])
 
+    def test_lambda_varargs(self):
+        node, c = self.checkChains( "lambda *args: args", [])
+        self.assertEqual(c.dump_chains(node.body[0].value), ['args -> (args -> (Lambda -> ()))'])
+    
+    def test_lambda_kwargs(self):
+        node, c = self.checkChains( "lambda **kwargs: kwargs", [])
+        self.assertEqual(c.dump_chains(node.body[0].value), ['kwargs -> (kwargs -> (Lambda -> ()))'])
+
     def test_multiple_import_as(self):
         code = "import x as y, z; y"
         self.checkChains(code, ["y -> (y -> ())", "z -> ()"])

Variable lenght arguments in lambda are ignored
```python
lambda *args: args
```

The code above generates the following warning: 

```
W: unbound identifier 'args' at ./test.py:1:14
```
tests/test_chains.py::TestDefUseChains::test_lambda_kwargs tests/test_chains.py::TestDefUseChains::test_lambda_varargs
tests/test_chains.py::TestDefUseChains::test_annotation_in_functions_locals tests/test_chains.py::TestDefUseChains::test_annotation_in_inner_functions_locals tests/test_chains.py::TestDefUseChains::test_annotation_inner_class tests/test_chains.py::TestDefUseChains::test_annotation_inner_inner_fn tests/test_chains.py::TestDefUseChains::test_annotation_unbound tests/test_chains.py::TestDefUseChains::test_annotation_unbound_pep563 tests/test_chains.py::TestDefUseChains::test_annotation_use_upper_scope_variables tests/test_chains.py::TestDefUseChains::test_annotation_uses_class_level_name tests/test_chains.py::TestDefUseChains::test_annotation_very_nested tests/test_chains.py::TestDefUseChains::test_arg_annotation tests/test_chains.py::TestDefUseChains::test_assign_in_loop tests/test_chains.py::TestDefUseChains::test_assign_in_loop_in_conditional tests/test_chains.py::TestDefUseChains::test_assign_in_while_in_conditional tests/test_chains.py::TestDefUseChains::test_assign_uses_class_level_name tests/test_chains.py::TestDefUseChains::test_assign_uses_class_level_same_name tests/test_chains.py::TestDefUseChains::test_attr tests/test_chains.py::TestDefUseChains::test_attribute_assignment tests/test_chains.py::TestDefUseChains::test_augassign tests/test_chains.py::TestDefUseChains::test_augassign_in_loop tests/test_chains.py::TestDefUseChains::test_augassign_undefined_global tests/test_chains.py::TestDefUseChains::test_base_class_uses_class_level_same_name tests/test_chains.py::TestDefUseChains::test_break_in_loop tests/test_chains.py::TestDefUseChains::test_call_assignment tests/test_chains.py::TestDefUseChains::test_class_base tests/test_chains.py::TestDefUseChains::test_class_decorator tests/test_chains.py::TestDefUseChains::test_class_scope_comprehension tests/test_chains.py::TestDefUseChains::test_class_scope_comprehension_invalid tests/test_chains.py::TestDefUseChains::test_complex_for_orelse tests/test_chains.py::TestDefUseChains::test_complex_while_orelse tests/test_chains.py::TestDefUseChains::test_continue_in_loop tests/test_chains.py::TestDefUseChains::test_def_used_in_self_default tests/test_chains.py::TestDefUseChains::test_expanded_augassign tests/test_chains.py::TestDefUseChains::test_expression_chain tests/test_chains.py::TestDefUseChains::test_for_break tests/test_chains.py::TestDefUseChains::test_for_pass tests/test_chains.py::TestDefUseChains::test_functiondef_returns tests/test_chains.py::TestDefUseChains::test_future_annotation_class_var tests/test_chains.py::TestDefUseChains::test_if_both_branch tests/test_chains.py::TestDefUseChains::test_if_false_branch tests/test_chains.py::TestDefUseChains::test_if_in_loop tests/test_chains.py::TestDefUseChains::test_if_true_branch tests/test_chains.py::TestDefUseChains::test_ifexp_chain tests/test_chains.py::TestDefUseChains::test_import_dotted_name_binds_first_name tests/test_chains.py::TestDefUseChains::test_import_from tests/test_chains.py::TestDefUseChains::test_import_from_as tests/test_chains.py::TestDefUseChains::test_lambda_defaults tests/test_chains.py::TestDefUseChains::test_lookup_scopes tests/test_chains.py::TestDefUseChains::test_maybe_unbound_identifier_message_format tests/test_chains.py::TestDefUseChains::test_method_annotation_unbound tests/test_chains.py::TestDefUseChains::test_method_annotation_unbound_pep563 tests/test_chains.py::TestDefUseChains::test_method_function_conflict tests/test_chains.py::TestDefUseChains::test_multiple_import_as tests/test_chains.py::TestDefUseChains::test_multiple_import_from_as tests/test_chains.py::TestDefUseChains::test_multiple_wildcards_may_bind tests/test_chains.py::TestDefUseChains::test_named_expr_complex tests/test_chains.py::TestDefUseChains::test_named_expr_comprehension tests/test_chains.py::TestDefUseChains::test_named_expr_comprehension_invalid tests/test_chains.py::TestDefUseChains::test_named_expr_simple tests/test_chains.py::TestDefUseChains::test_named_expr_with_rename tests/test_chains.py::TestDefUseChains::test_nested_if tests/test_chains.py::TestDefUseChains::test_nested_if_else tests/test_chains.py::TestDefUseChains::test_nested_while tests/test_chains.py::TestDefUseChains::test_no_unbound_local_identifier_in_comp tests/test_chains.py::TestDefUseChains::test_pep0563_annotations tests/test_chains.py::TestDefUseChains::test_pep563_self_referential_annotation tests/test_chains.py::TestDefUseChains::test_pep563_type_alias_override_class tests/test_chains.py::TestDefUseChains::test_read_global_from_branch tests/test_chains.py::TestDefUseChains::test_reassign_in_loop tests/test_chains.py::TestDefUseChains::test_redef_try_except tests/test_chains.py::TestDefUseChains::test_redefinition_in_comp tests/test_chains.py::TestDefUseChains::test_simple_except tests/test_chains.py::TestDefUseChains::test_simple_expression tests/test_chains.py::TestDefUseChains::test_simple_for tests/test_chains.py::TestDefUseChains::test_simple_for_orelse tests/test_chains.py::TestDefUseChains::test_simple_import tests/test_chains.py::TestDefUseChains::test_simple_import_as tests/test_chains.py::TestDefUseChains::test_simple_lambda tests/test_chains.py::TestDefUseChains::test_simple_print tests/test_chains.py::TestDefUseChains::test_simple_redefinition tests/test_chains.py::TestDefUseChains::test_simple_try tests/test_chains.py::TestDefUseChains::test_simple_try_except tests/test_chains.py::TestDefUseChains::test_simple_while tests/test_chains.py::TestDefUseChains::test_star_assignment tests/test_chains.py::TestDefUseChains::test_star_assignment_nested tests/test_chains.py::TestDefUseChains::test_star_import_with_conditional_redef tests/test_chains.py::TestDefUseChains::test_straight_raise tests/test_chains.py::TestDefUseChains::test_try_except tests/test_chains.py::TestDefUseChains::test_type_destructuring_for tests/test_chains.py::TestDefUseChains::test_type_destructuring_list tests/test_chains.py::TestDefUseChains::test_type_destructuring_starred tests/test_chains.py::TestDefUseChains::test_type_destructuring_tuple tests/test_chains.py::TestDefUseChains::test_unbound_class_variable tests/test_chains.py::TestDefUseChains::test_unbound_class_variable2 tests/test_chains.py::TestDefUseChains::test_unbound_class_variable3 tests/test_chains.py::TestDefUseChains::test_unbound_class_variable4 tests/test_chains.py::TestDefUseChains::test_unbound_class_variable5 tests/test_chains.py::TestDefUseChains::test_unbound_class_variable_reference_message_format tests/test_chains.py::TestDefUseChains::test_unbound_identifier_message_format tests/test_chains.py::TestDefUseChains::test_unbound_local_identifier_in_augassign tests/test_chains.py::TestDefUseChains::test_unbound_local_identifier_in_func tests/test_chains.py::TestDefUseChains::test_unbound_local_identifier_in_method tests/test_chains.py::TestDefUseChains::test_unbound_local_identifier_nonlocal tests/test_chains.py::TestDefUseChains::test_while_break tests/test_chains.py::TestDefUseChains::test_while_cond_break tests/test_chains.py::TestDefUseChains::test_while_cond_continue tests/test_chains.py::TestDefUseChains::test_while_nested_break tests/test_chains.py::TestDefUseChains::test_while_orelse_break tests/test_chains.py::TestDefUseChains::test_wilcard_import_annotation tests/test_chains.py::TestDefUseChains::test_wilcard_import_annotation_and_global_scope tests/test_chains.py::TestDefUseChains::test_wildcard_may_override tests/test_chains.py::TestDefUseChains::test_with_handler tests/test_chains.py::TestUseDefChains::test_call tests/test_chains.py::TestUseDefChains::test_simple_expression