diff --git a/django/http/utils.py b/django/http/utils.py
index 90155cd2ed..5dcac06dcf 100644
--- a/django/http/utils.py
+++ b/django/http/utils.py
@@ -17,7 +17,7 @@ def fix_location_header(request, response):
     Code constructing response objects is free to insert relative paths, as
     this function converts them to absolute paths.
     """
-    if 'Location' in response and request.get_host():
+    if 'Location' in response:
         response['Location'] = request.build_absolute_uri(response['Location'])
     return response
 
diff --git a/tests/http_utils/tests.py b/tests/http_utils/tests.py
index 9105e64ee4..3225bfebf1 100644
--- a/tests/http_utils/tests.py
+++ b/tests/http_utils/tests.py
@@ -3,8 +3,8 @@ from __future__ import unicode_literals
 import io
 import gzip
 
-from django.http import HttpRequest, HttpResponse, StreamingHttpResponse
-from django.http.utils import conditional_content_removal
+from django.http import HttpRequest, HttpResponse, HttpResponseRedirect, StreamingHttpResponse
+from django.http.utils import conditional_content_removal, fix_location_header
 from django.test import TestCase
 
 
@@ -69,3 +69,14 @@ class HttpUtilTests(TestCase):
         res = StreamingHttpResponse(['abc'])
         conditional_content_removal(req, res)
         self.assertEqual(b''.join(res), b'')
+
+    def test_fix_location_without_get_host(self):
+        """
+        Tests that you can return an absolute redirect when the request
+        host is not in ALLOWED_HOSTS. Issue #20472
+        """
+        request = HttpRequest()
+        def bomb():
+            self.assertTrue(False)
+        request.get_host = bomb
+        fix_location_header(request, HttpResponseRedirect('http://example.com'))