diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 9a5666b143..27c6859c61 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -553,7 +553,10 @@ class Query(object):
         columns = set()
         orig_opts = self.model._meta
         seen = {}
-        must_include = {self.model: set([orig_opts.pk])}
+        if orig_opts.proxy:
+            must_include = {orig_opts.proxy_for_model: set([orig_opts.pk])}
+        else:
+            must_include = {self.model: set([orig_opts.pk])}
         for field_name in field_names:
             parts = field_name.split(LOOKUP_SEP)
             cur_model = self.model
diff --git a/tests/regressiontests/defer_regress/models.py b/tests/regressiontests/defer_regress/models.py
index 8db8c29960..4e4ab0a515 100644
--- a/tests/regressiontests/defer_regress/models.py
+++ b/tests/regressiontests/defer_regress/models.py
@@ -34,3 +34,7 @@ class Leaf(models.Model):
 class ResolveThis(models.Model):
     num = models.FloatField()
     name = models.CharField(max_length=16)
+
+class Proxy(Item):
+    class Meta:
+        proxy = True
diff --git a/tests/regressiontests/defer_regress/tests.py b/tests/regressiontests/defer_regress/tests.py
index 6f1b023b5b..fbcf85e078 100644
--- a/tests/regressiontests/defer_regress/tests.py
+++ b/tests/regressiontests/defer_regress/tests.py
@@ -7,7 +7,7 @@ from django.db import connection
 from django.db.models.loading import cache
 from django.test import TestCase
 
-from models import ResolveThis, Item, RelatedItem, Child, Leaf
+from models import ResolveThis, Item, RelatedItem, Child, Leaf, Proxy
 
 
 class DeferRegressionTest(TestCase):
@@ -111,6 +111,7 @@ class DeferRegressionTest(TestCase):
                 Child,
                 Item,
                 Leaf,
+                Proxy,
                 RelatedItem,
                 ResolveThis,
             ]
@@ -139,6 +140,7 @@ class DeferRegressionTest(TestCase):
                 "Leaf_Deferred_name_value",
                 "Leaf_Deferred_second_child_value",
                 "Leaf_Deferred_value",
+                "Proxy",
                 "RelatedItem",
                 "RelatedItem_Deferred_",
                 "RelatedItem_Deferred_item_id",
@@ -146,6 +148,21 @@ class DeferRegressionTest(TestCase):
             ]
         )
 
+    def test_only_and_defer_usage_on_proxy_models(self):
+        # Regression for #15790 - only() broken for proxy models
+        proxy = Proxy.objects.create(name="proxy", value=42)
+
+        msg = 'QuerySet.only() return bogus results with proxy models'
+        dp = Proxy.objects.only('other_value').get(pk=proxy.pk)
+        self.assertEqual(dp.name, proxy.name, msg=msg)
+        self.assertEqual(dp.value, proxy.value, msg=msg)
+
+        # also test things with .defer()
+        msg = 'QuerySet.defer() return bogus results with proxy models'
+        dp = Proxy.objects.defer('name', 'text', 'value').get(pk=proxy.pk)
+        self.assertEqual(dp.name, proxy.name, msg=msg)
+        self.assertEqual(dp.value, proxy.value, msg=msg)
+
     def test_resolve_columns(self):
         rt = ResolveThis.objects.create(num=5.0, name='Foobar')
         qs = ResolveThis.objects.defer('num')