diff --git a/django/contrib/admin/options.py b/django/contrib/admin/options.py
index fdc648060c..8b0af2b78d 100644
--- a/django/contrib/admin/options.py
+++ b/django/contrib/admin/options.py
@@ -1083,7 +1083,7 @@ class ModelAdmin(BaseModelAdmin):
                 attr = obj._meta.pk.attname
             value = obj.serializable_value(attr)
             popup_response_data = json.dumps({
-                'value': value,
+                'value': six.text_type(value),
                 'obj': six.text_type(obj),
             })
             return SimpleTemplateResponse('admin/popup_response.html', {
diff --git a/tests/admin_views/models.py b/tests/admin_views/models.py
index c105c42e4a..aa4476c9ed 100644
--- a/tests/admin_views/models.py
+++ b/tests/admin_views/models.py
@@ -16,6 +16,7 @@ from django.db import models
 from django.utils.encoding import python_2_unicode_compatible
 
 
+@python_2_unicode_compatible
 class Section(models.Model):
     """
     A simple section that links to articles, to test linking to related items
@@ -23,6 +24,9 @@ class Section(models.Model):
     """
     name = models.CharField(max_length=100)
 
+    def __str__(self):
+        return self.name
+
     @property
     def name_property(self):
         """
diff --git a/tests/admin_views/tests.py b/tests/admin_views/tests.py
index 457ac47646..49afb860c5 100644
--- a/tests/admin_views/tests.py
+++ b/tests/admin_views/tests.py
@@ -4481,8 +4481,10 @@ class SeleniumAdminViewsFirefoxTests(AdminSeleniumWebDriverTestCase):
         """
         list_editable foreign keys have add/change popups.
         """
+        from selenium.webdriver.support.ui import Select
         s1 = Section.objects.create(name='Test section')
         Article.objects.create(
+            title='foo',
             content='<p>Middle content</p>',
             date=datetime.datetime(2008, 3, 18, 11, 54, 58),
             section=s1,
@@ -4494,16 +4496,24 @@ class SeleniumAdminViewsFirefoxTests(AdminSeleniumWebDriverTestCase):
         self.wait_for_popup()
         self.selenium.switch_to.window(self.selenium.window_handles[-1])
         self.wait_for_text('#content h1', 'Change section')
-        self.selenium.close()
+        name_input = self.selenium.find_element_by_id('id_name')
+        name_input.clear()
+        name_input.send_keys('edited section')
+        self.selenium.find_element_by_xpath('//input[@value="Save"]').click()
         self.selenium.switch_to.window(self.selenium.window_handles[0])
+        select = Select(self.selenium.find_element_by_id('id_form-0-section'))
+        self.assertEqual(select.first_selected_option.text, 'edited section')
 
         # Add popup
         self.selenium.find_element_by_id('add_id_form-0-section').click()
         self.wait_for_popup()
         self.selenium.switch_to.window(self.selenium.window_handles[-1])
         self.wait_for_text('#content h1', 'Add section')
-        self.selenium.close()
+        self.selenium.find_element_by_id('id_name').send_keys('new section')
+        self.selenium.find_element_by_xpath('//input[@value="Save"]').click()
         self.selenium.switch_to.window(self.selenium.window_handles[0])
+        select = Select(self.selenium.find_element_by_id('id_form-0-section'))
+        self.assertEqual(select.first_selected_option.text, 'new section')
 
 
 class SeleniumAdminViewsChromeTests(SeleniumAdminViewsFirefoxTests):