diff --git a/qutebrowser/browser/network/networkmanager.py b/qutebrowser/browser/network/networkmanager.py
index 97e88008c..52dc4f017 100644
--- a/qutebrowser/browser/network/networkmanager.py
+++ b/qutebrowser/browser/network/networkmanager.py
@@ -359,18 +359,11 @@ class NetworkManager(QNetworkAccessManager):
         req.setRawHeader('DNT'.encode('ascii'), dnt)
         req.setRawHeader('X-Do-Not-Track'.encode('ascii'), dnt)
 
-        def same_domain():
-            tabbed_browser = objreg.get('tabbed-browser', scope='window', window=self._win_id)
-            view = tabbed_browser.currentWidget()
-            print(req.url().host() == view.url().host(), repr(view.url().host()), repr(req.url().host()))
-            # TODO: We probably want to allow headers if we're on test.com and
-            # doing a request to www.test.com? Or maybe a new settings value for
-            # this?
-            return req.url().host() == view.url().host()
-
+        current_url = objreg.get('tabbed-browser', scope='window',
+                                 window=self._win_id).currentWidget().url()
         if (config.get('network', 'referer-header') == 'never' or
                 (config.get('network', 'referer-header') == 'same-domain' and
-                    same_domain())):
+                    urlutils.same_domain(req.url(), current_url))):
             # Note: using ''.encode('ascii') sends a header with no value,
             # instead of no header at all
             req.setRawHeader('Referer'.encode('ascii'), QByteArray())
diff --git a/qutebrowser/config/configtypes.py b/qutebrowser/config/configtypes.py
index 8e9c27697..cb1bc744a 100644
--- a/qutebrowser/config/configtypes.py
+++ b/qutebrowser/config/configtypes.py
@@ -1471,7 +1471,6 @@ class Referer(BaseType):
                                    " shouldn't break any sites."))
 
 
-
 class UserAgent(BaseType):
 
     """The user agent to use."""
diff --git a/qutebrowser/utils/urlutils.py b/qutebrowser/utils/urlutils.py
index 143e7cfc5..fbe280199 100644
--- a/qutebrowser/utils/urlutils.py
+++ b/qutebrowser/utils/urlutils.py
@@ -392,6 +392,33 @@ def get_errstring(url, base="Invalid URL"):
         return base
 
 
+def same_domain(url1, url2):
+    """Check if url1 and url2 belong to the same website.
+
+    This will use a "public suffix list" to determine what a "top level domain"
+    is. All further domains are ignored.
+
+    For example example.com and www.example.com are considered the same. but
+    example.co.uk and test.co.uk are not.
+
+    Return:
+        True if the domains are the same, False otherwise.
+    """
+    if not url1.isValid():
+        raise ValueError(get_errstring(url1))
+    if not url2.isValid():
+        raise ValueError(get_errstring(url2))
+
+    suffix1 = url1.topLevelDomain()
+    suffix2 = url2.topLevelDomain()
+    if not suffix1 == suffix2:
+        return False
+
+    domain1 = url1.host()[:-len(suffix1)].split('.')[-1]
+    domain2 = url2.host()[:-len(suffix2)].split('.')[-1]
+    return domain1 == domain2
+
+
 class FuzzyUrlError(Exception):
 
     """Exception raised by fuzzy_url on problems.
diff --git a/tests/utils/test_urlutils.py b/tests/utils/test_urlutils.py
index 264de925b..4f027ceff 100644
--- a/tests/utils/test_urlutils.py
+++ b/tests/utils/test_urlutils.py
@@ -227,3 +227,32 @@ class TestFilenameFromUrl:
         """Test with an URL with no path."""
         url = QUrl('http://qutebrowser.org/')
         assert urlutils.filename_from_url(url) == 'qutebrowser.org.html'
+
+
+class TestSameDomain:
+
+    """Tests for dame_domain."""
+
+    def test_same_domains(self):
+        """Test for domains that should be considered the same."""
+        hosts = (
+            ('http://example.com', 'http://www.example.com'),
+            ('http://bbc.co.uk', 'https://www.bbc.co.uk'),
+            ('http://many.levels.of.domains.example.com', 'http://www.example.com'),
+        )
+
+        for host1, host2 in hosts:
+            assert urlutils.same_domain(QUrl(host1), QUrl(host2))
+            assert urlutils.same_domain(QUrl(host2), QUrl(host1))
+
+    def test_not_same_domains(self):
+        """Test for domains that should be NOT considered the same."""
+        hosts = (
+            ('http://bbc.co.uk', 'http://example.co.uk'),
+            ('https://example.kids.museum', 'http://example.kunst.museum'),
+            ('http://idn.иком.museum', 'http://idn.ירושלים.museum')
+        )
+
+        for host1, host2 in hosts:
+            assert not urlutils.same_domain(QUrl(host1), QUrl(host2))
+            assert not urlutils.same_domain(QUrl(host2), QUrl(host1))