diff --git a/AUTHORS b/AUTHORS
index 75c894021f..ac4ab8410e 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -255,6 +255,7 @@ answer newbie questions, and generally made Django that much better:
     enlight
     Enrico <rico.bl@gmail.com>
     Eric Boersma <eric.boersma@gmail.com>
+    Eric Brandwein <brandweineric@gmail.com>
     Eric Floehr <eric@intellovations.com>
     Eric Florenzano <floguy@gmail.com>
     Eric Holscher <http://ericholscher.com>
diff --git a/django/urls/resolvers.py b/django/urls/resolvers.py
index 91d21c9da9..4f2aefc9b0 100644
--- a/django/urls/resolvers.py
+++ b/django/urls/resolvers.py
@@ -469,6 +469,8 @@ class URLResolver:
                                     )
                                 )
                         for namespace, (prefix, sub_pattern) in url_pattern.namespace_dict.items():
+                            current_converters = url_pattern.pattern.converters
+                            sub_pattern.pattern.converters.update(current_converters)
                             namespaces[namespace] = (p_pattern + prefix, sub_pattern)
                         for app_name, namespace_list in url_pattern.app_dict.items():
                             apps.setdefault(app_name, []).extend(namespace_list)
diff --git a/tests/urlpatterns/path_base64_urls.py b/tests/urlpatterns/path_base64_urls.py
index 9b69f929fe..afd11ac9f6 100644
--- a/tests/urlpatterns/path_base64_urls.py
+++ b/tests/urlpatterns/path_base64_urls.py
@@ -4,8 +4,16 @@ from . import converters, views
 
 register_converter(converters.Base64Converter, 'base64')
 
+subsubpatterns = [
+    path('<base64:last_value>/', views.empty_view, name='subsubpattern-base64'),
+]
+
 subpatterns = [
     path('<base64:value>/', views.empty_view, name='subpattern-base64'),
+    path(
+        '<base64:value>/',
+        include((subsubpatterns, 'second-layer-namespaced-base64'), 'instance-ns-base64')
+    ),
 ]
 
 urlpatterns = [
diff --git a/tests/urlpatterns/tests.py b/tests/urlpatterns/tests.py
index b3d97ec5b9..299258e56f 100644
--- a/tests/urlpatterns/tests.py
+++ b/tests/urlpatterns/tests.py
@@ -70,6 +70,13 @@ class SimplifiedURLTests(SimpleTestCase):
                 url = reverse(url_name, kwargs=kwargs)
                 self.assertEqual(url, expected)
 
+    @override_settings(ROOT_URLCONF='urlpatterns.path_base64_urls')
+    def test_converter_reverse_with_second_layer_instance_namespace(self):
+        kwargs = included_kwargs.copy()
+        kwargs['last_value'] = b'world'
+        url = reverse('instance-ns-base64:subsubpattern-base64', kwargs=kwargs)
+        self.assertEqual(url, '/base64/aGVsbG8=/subpatterns/d29ybGQ=/d29ybGQ=/')
+
     def test_path_inclusion_is_matchable(self):
         match = resolve('/included_urls/extra/something/')
         self.assertEqual(match.url_name, 'inner-extra')