diff --git a/beniget/beniget.py b/beniget/beniget.py
index 50f035b..c964c50 100644
--- a/beniget/beniget.py
+++ b/beniget/beniget.py
@@ -1025,11 +1025,19 @@ class DefUseChains(ast.NodeVisitor):
     def visit_Lambda(self, node, step=DeclarationStep):
         if step is DeclarationStep:
             dnode = self.chains.setdefault(node, Def(node))
+            for default in node.args.defaults:
+                self.visit(default).add_user(dnode)
+            self._defered.append((node,
+                                  list(self._definitions),
+                                  list(self._scopes),
+                                  list(self._scope_depths),
+                                  list(self._precomputed_locals)))
             return dnode
         elif step is DefinitionStep:
             dnode = self.chains[node]
             with self.ScopeContext(node):
-                self.visit(node.args)
+                for a in node.args.args:
+                    self.visit(a)
                 self.visit(node.body).add_user(dnode)
             return dnode
         else:

diff --git a/tests/test_chains.py b/tests/test_chains.py
index e9d33f8..288ccc6 100644
--- a/tests/test_chains.py
+++ b/tests/test_chains.py
@@ -332,6 +332,22 @@ while done:
     def test_simple_import_as(self):
         code = "import x as y; y()"
         self.checkChains(code, ["y -> (y -> (Call -> ()))"])
+    
+    def test_simple_lambda(self):
+        node, c = self.checkChains( "lambda y: True", [])
+        self.assertEqual(c.dump_chains(node.body[0].value), ['y -> ()'])
+    
+    def test_lambda_defaults(self):
+        node, c = self.checkChains( "x=y=1;(lambda y, x=x: (True, x, y, z)); x=y=z=2", 
+                                   ['x -> (x -> (Lambda -> ()))',
+                                    'y -> ()', 
+                                    'x -> ()', 
+                                    'y -> ()',
+                                    'z -> (z -> (Tuple -> (Lambda -> ())))']) 
+        self.assertEqual(c.dump_chains(node.body[1].value), [
+            'y -> (y -> (Tuple -> (Lambda -> ())))',
+            'x -> (x -> (Tuple -> (Lambda -> ())))',
+        ])
 
     def test_multiple_import_as(self):
         code = "import x as y, z; y"

Regression in Lambda functions
This new test was passing in version 0.4.1 and now shows nothing

```python
    def test_simple_lambda(self):
        code = "lambda y: True"
        node = ast.parse(code)
        c = beniget.DefUseChains()
        c.visit(node)
        self.assertEqual(c.dump_chains(node), [])
        self.assertEqual(c.dump_chains(node.body[0].value), ['y -> ()'])
```
tests/test_chains.py::TestDefUseChains::test_lambda_defaults tests/test_chains.py::TestDefUseChains::test_simple_lambda
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_augassign tests/test_chains.py::TestDefUseChains::test_augassign_in_loop 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_class_base tests/test_chains.py::TestDefUseChains::test_class_decorator 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_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_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_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_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_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