diff --git a/django/contrib/gis/db/backends/adapter.py b/django/contrib/gis/db/backends/adapter.py
index 9766ef08c96..ca77124351b 100644
--- a/django/contrib/gis/db/backends/adapter.py
+++ b/django/contrib/gis/db/backends/adapter.py
@@ -8,6 +8,8 @@ class WKTAdapter(object):
         self.srid = geom.srid
 
     def __eq__(self, other):
+        if not isinstance(other, WKTAdapter):
+            return False
         return self.wkt == other.wkt and self.srid == other.srid
 
     def __str__(self):
diff --git a/django/contrib/gis/db/backends/postgis/adapter.py b/django/contrib/gis/db/backends/postgis/adapter.py
index 3f8603e50a1..c9b9841d55a 100644
--- a/django/contrib/gis/db/backends/postgis/adapter.py
+++ b/django/contrib/gis/db/backends/postgis/adapter.py
@@ -21,6 +21,8 @@ class PostGISAdapter(object):
             raise Exception('Error implementing psycopg2 protocol. Is psycopg2 installed?')
 
     def __eq__(self, other):
+        if not isinstance(other, PostGISAdapter):
+            return False
         return (self.ewkb == other.ewkb) and (self.srid == other.srid)
 
     def __str__(self):
diff --git a/django/contrib/gis/tests/geoapp/test_regress.py b/django/contrib/gis/tests/geoapp/test_regress.py
index 02b1ff08eb6..45070b0c935 100644
--- a/django/contrib/gis/tests/geoapp/test_regress.py
+++ b/django/contrib/gis/tests/geoapp/test_regress.py
@@ -2,7 +2,7 @@ from datetime import datetime
 from django.contrib.gis.tests.utils import no_mysql, no_spatialite
 from django.contrib.gis.shortcuts import render_to_kmz
 from django.test import TestCase
-from models import City, PennsylvaniaCity
+from models import City, PennsylvaniaCity, State
 
 class GeoRegressionTests(TestCase):
 
@@ -43,3 +43,13 @@ class GeoRegressionTests(TestCase):
         mansfield = PennsylvaniaCity.objects.create(name='Mansfield', county='Tioga', point='POINT(-77.071445 41.823881)',
                                                     founded=founded)
         self.assertEqual(founded, PennsylvaniaCity.objects.dates('founded', 'day')[0])
+
+    def test05_empty_count(self):
+         "Testing that PostGISAdapter.__eq__ does check empty strings, see #13670"
+         # contrived example, but need a geo lookup paired with an id__in lookup
+         pueblo = City.objects.get(name='Pueblo')
+         state = State.objects.filter(poly__contains=pueblo.point)
+         cities_within_state = City.objects.filter(id__in=state)
+
+         # .count() should not throw TypeError in __eq__
+         self.assertEqual(cities_within_state.count(), 1)