diff --git a/django/utils/http.py b/django/utils/http.py
index d732a9c825..33515eb410 100644
--- a/django/utils/http.py
+++ b/django/utils/http.py
@@ -33,6 +33,11 @@ ASCTIME_DATE = re.compile(r'^\w{3} %s %s %s %s$' % (__M, __D2, __T, __Y))
 RFC3986_GENDELIMS = str(":/?#[]@")
 RFC3986_SUBDELIMS = str("!$&'()*+,;=")
 
+PROTOCOL_TO_PORT = {
+    'http': 80,
+    'https': 443,
+}
+
 
 def urlquote(url, safe='/'):
     """
@@ -253,8 +258,10 @@ def same_origin(url1, url2):
     """
     p1, p2 = urlparse(url1), urlparse(url2)
     try:
-        return (p1.scheme, p1.hostname, p1.port) == (p2.scheme, p2.hostname, p2.port)
-    except ValueError:
+        o1 = (p1.scheme, p1.hostname, p1.port or PROTOCOL_TO_PORT[p1.scheme])
+        o2 = (p2.scheme, p2.hostname, p2.port or PROTOCOL_TO_PORT[p2.scheme])
+        return o1 == o2
+    except (ValueError, KeyError):
         return False
 
 
diff --git a/tests/utils_tests/test_http.py b/tests/utils_tests/test_http.py
index 19bfa79f1a..7e48fe70a7 100644
--- a/tests/utils_tests/test_http.py
+++ b/tests/utils_tests/test_http.py
@@ -18,6 +18,9 @@ class TestUtilsHttp(unittest.TestCase):
         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/'))
+        # No port given but according to RFC6454 still the same origin
+        self.assertTrue(http.same_origin('http://foo.com', 'http://foo.com:80/'))
+        self.assertTrue(http.same_origin('https://foo.com', 'https://foo.com:443/'))
 
     def test_same_origin_false(self):
         # Different scheme
@@ -28,6 +31,9 @@ class TestUtilsHttp(unittest.TestCase):
         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'))
+        # No port given
+        self.assertFalse(http.same_origin('http://foo.com', 'http://foo.com:8000/'))
+        self.assertFalse(http.same_origin('https://foo.com', 'https://foo.com:8000/'))
 
     def test_urlencode(self):
         # 2-tuples (the norm)