diff --git a/django/contrib/gis/forms/widgets.py b/django/contrib/gis/forms/widgets.py
index e9518f4e7e..cc82f41563 100644
--- a/django/contrib/gis/forms/widgets.py
+++ b/django/contrib/gis/forms/widgets.py
@@ -43,6 +43,7 @@ class BaseGeometryWidget(Widget):
         return None
 
     def get_context(self, name, value, attrs):
+        context = super(BaseGeometryWidget, self).get_context(name, value, attrs)
         # If a string reaches here (via a validation error on another
         # field) then just reconstruct the Geometry.
         if value and isinstance(value, six.string_types):
@@ -64,7 +65,7 @@ class BaseGeometryWidget(Widget):
         if attrs is None:
             attrs = {}
 
-        context = self.build_attrs(self.attrs, dict(
+        context.update(self.build_attrs(self.attrs, dict(
             name=name,
             module='geodjango_%s' % name.replace('-', '_'),  # JS-safe
             serialized=self.serialize(value),
@@ -72,7 +73,7 @@ class BaseGeometryWidget(Widget):
             STATIC_URL=settings.STATIC_URL,
             LANGUAGE_BIDI=translation.get_language_bidi(),
             **attrs
-        ))
+        )))
         return context
 
 
diff --git a/docs/releases/1.11.1.txt b/docs/releases/1.11.1.txt
index 53c43443aa..1f475ee736 100644
--- a/docs/releases/1.11.1.txt
+++ b/docs/releases/1.11.1.txt
@@ -40,3 +40,5 @@ Bugfixes
 * Restored the output of the ``class`` attribute in the ``<ul>`` of widgets
   that use the ``multiple_input.html`` template. This fixes
   ``ModelAdmin.radio_fields`` with ``admin.HORIZONTAL`` (:ticket:`28059`).
+
+* Fixed crash in ``BaseGeometryWidget.subwidgets()`` (:ticket:`28039`).
diff --git a/tests/gis_tests/test_geoforms.py b/tests/gis_tests/test_geoforms.py
index 437a828e47..7bec54edf5 100644
--- a/tests/gis_tests/test_geoforms.py
+++ b/tests/gis_tests/test_geoforms.py
@@ -351,7 +351,27 @@ class OSMWidgetTest(SimpleTestCase):
 
 
 @skipUnlessDBFeature("gis_enabled")
-class CustomGeometryWidgetTest(SimpleTestCase):
+class GeometryWidgetTests(SimpleTestCase):
+
+    def test_subwidgets(self):
+        widget = forms.BaseGeometryWidget()
+        self.assertEqual(
+            list(widget.subwidgets('name', 'value')),
+            [{
+                'is_hidden': False,
+                'attrs': {
+                    'map_srid': 4326,
+                    'map_width': 600,
+                    'geom_type': 'GEOMETRY',
+                    'map_height': 400,
+                    'display_raw': False,
+                },
+                'name': 'name',
+                'template_name': '',
+                'value': 'value',
+                'required': False,
+            }]
+        )
 
     def test_custom_serialization_widget(self):
         class CustomGeometryWidget(forms.BaseGeometryWidget):