diff --git a/tests/modeltests/defer/tests.py b/tests/modeltests/defer/tests.py
index 88aac0c9e5..09138293af 100644
--- a/tests/modeltests/defer/tests.py
+++ b/tests/modeltests/defer/tests.py
@@ -146,6 +146,15 @@ class DeferTests(TestCase):
         obj.save()
 
     def test_defer_proxy(self):
-        # using select related and only should not result in Exception
-        for obj in ChildProxy.objects.all().select_related().only('id'):
-            continue
+        """
+        Ensure select_related together with only on a proxy model behaves
+        as expected. See #17876.
+        """
+        related = Secondary.objects.create(first='x1', second='x2')
+        ChildProxy.objects.create(name='p1', value='xx', related=related)
+        children = ChildProxy.objects.all().select_related().only('id', 'name')
+        self.assertEqual(len(children), 1)
+        child = children[0]
+        self.assert_delayed(child, 1)
+        self.assertEqual(child.name, 'p1')
+        self.assertEqual(child.value, 'xx')