diff --git a/django/middleware/csrf.py b/django/middleware/csrf.py
index 2602ce88243f0..b5a85795b2452 100644
--- a/django/middleware/csrf.py
+++ b/django/middleware/csrf.py
@@ -13,6 +13,7 @@
 from django.core.urlresolvers import get_callable
 from django.utils.cache import patch_vary_headers
 from django.utils.hashcompat import md5_constructor
+from django.utils.http import same_origin
 from django.utils.log import getLogger
 from django.utils.safestring import mark_safe
 from django.utils.crypto import constant_time_compare
@@ -161,10 +162,9 @@ def process_view(self, request, callback, callback_args, callback_kwargs):
                     )
                     return self._reject(request, REASON_NO_REFERER)
 
-                # The following check ensures that the referer is HTTPS,
-                # the domains match and the ports match - the same origin policy.
+                # Note that request.get_host() includes the port
                 good_referer = 'https://%s/' % request.get_host()
-                if not referer.startswith(good_referer):
+                if not same_origin(referer, good_referer):
                     reason = REASON_BAD_REFERER % (referer, good_referer)
                     logger.warning('Forbidden (%s): %s' % (reason, request.path),
                         extra={
diff --git a/django/utils/http.py b/django/utils/http.py
index ae2dabf7363d2..c93a338c30810 100644
--- a/django/utils/http.py
+++ b/django/utils/http.py
@@ -3,6 +3,7 @@
 import re
 import sys
 import urllib
+import urlparse
 from email.Utils import formatdate
 
 from django.utils.encoding import smart_str, force_unicode
@@ -186,3 +187,20 @@ def quote_etag(etag):
     """
     return '"%s"' % etag.replace('\\', '\\\\').replace('"', '\\"')
 
+if sys.version_info >= (2, 6):
+    def same_origin(url1, url2):
+        """
+        Checks if two URLs are 'same-origin'
+        """
+        p1, p2 = urlparse.urlparse(url1), urlparse.urlparse(url2)
+        return (p1.scheme, p1.hostname, p1.port) == (p2.scheme, p2.hostname, p2.port)
+else:
+    # Python 2.4, 2.5 compatibility. This actually works for Python 2.6 and
+    # above, but the above definition is much more obviously correct and so is
+    # preferred going forward.
+    def same_origin(url1, url2):
+        """
+        Checks if two URLs are 'same-origin'
+        """
+        p1, p2 = urlparse.urlparse(url1), urlparse.urlparse(url2)
+        return p1[0:2] == p2[0:2]
diff --git a/tests/regressiontests/csrf_tests/tests.py b/tests/regressiontests/csrf_tests/tests.py
index 396f98f419bc1..d75adc917bb02 100644
--- a/tests/regressiontests/csrf_tests/tests.py
+++ b/tests/regressiontests/csrf_tests/tests.py
@@ -382,3 +382,16 @@ def test_https_good_referer(self):
         req.META['HTTP_REFERER'] = 'https://www.example.com/somepage'
         req2 = CsrfViewMiddleware().process_view(req, post_form_view, (), {})
         self.assertEqual(None, req2)
+
+    def test_https_good_referer_2(self):
+        """
+        Test that a POST HTTPS request with a good referer is accepted
+        where the referer contains no trailing slash
+        """
+        # See ticket #15617
+        req = self._get_POST_request_with_token()
+        req._is_secure = True
+        req.META['HTTP_HOST'] = 'www.example.com'
+        req.META['HTTP_REFERER'] = 'https://www.example.com'
+        req2 = CsrfViewMiddleware().process_view(req, post_form_view, (), {})
+        self.assertEqual(None, req2)
diff --git a/tests/regressiontests/utils/http.py b/tests/regressiontests/utils/http.py
new file mode 100644
index 0000000000000..83a4a7f54d7ed
--- /dev/null
+++ b/tests/regressiontests/utils/http.py
@@ -0,0 +1,23 @@
+from django.utils import http
+from django.utils import unittest
+
+class TestUtilsHttp(unittest.TestCase):
+
+    def test_same_origin_true(self):
+        # Identical
+        self.assertTrue(http.same_origin('http://foo.com/', 'http://foo.com/'))
+        # One with trailing slash - see #15617
+        self.assertTrue(http.same_origin('http://foo.com', 'http://foo.com/'))
+        self.assertTrue(http.same_origin('http://foo.com/', 'http://foo.com'))
+        # With port
+        self.assertTrue(http.same_origin('https://foo.com:8000', 'https://foo.com:8000/'))
+
+    def test_same_origin_false(self):
+        # Different scheme
+        self.assertFalse(http.same_origin('http://foo.com', 'https://foo.com'))
+        # Different host
+        self.assertFalse(http.same_origin('http://foo.com', 'http://goo.com'))
+        # Different host again
+        self.assertFalse(http.same_origin('http://foo.com', 'http://foo.com.evil.com'))
+        # Different port
+        self.assertFalse(http.same_origin('http://foo.com:8000', 'http://foo.com:8001'))
diff --git a/tests/regressiontests/utils/tests.py b/tests/regressiontests/utils/tests.py
index 6d3bbfa86cc17..5c4c0602e8f12 100644
--- a/tests/regressiontests/utils/tests.py
+++ b/tests/regressiontests/utils/tests.py
@@ -7,6 +7,7 @@
 from module_loading import *
 from termcolors import *
 from html import *
+from http import *
 from checksums import *
 from text import *
 from simplelazyobject import *