diff --git a/linkcheck/url.py b/linkcheck/url.py
index 46e1efd3..fa16bde4 100644
--- a/linkcheck/url.py
+++ b/linkcheck/url.py
@@ -601,7 +601,13 @@ def is_duplicate_content_url(url1, url2):
     if url1 == url2:
         return True
     if url2 in url1:
-        return shorten_duplicate_content_url(url1) == url2
+        url1 = shorten_duplicate_content_url(url1)
+        if not url2.endswith('/') and url1.endswith('/'):
+            url2 += '/'
+        return url1 == url2
     if url1 in url2:
-        return shorten_duplicate_content_url(url2) == url1
+        url2 = shorten_duplicate_content_url(url2)
+        if not url1.endswith('/') and url2.endswith('/'):
+            url1 += '/'
+        return url1 == url2
     return False
diff --git a/tests/test_url.py b/tests/test_url.py
index 0c07a004..fdb663c9 100644
--- a/tests/test_url.py
+++ b/tests/test_url.py
@@ -554,3 +554,13 @@ class TestUrl (unittest.TestCase):
     @need_network
     def test_get_content (self):
         linkcheck.url.get_content('http://www.debian.org/')
+
+    def test_duplicate_urls(self):
+        is_dup = linkcheck.url.is_duplicate_content_url
+        self.assertTrue(is_dup("http://example.org", "http://example.org"))
+        self.assertTrue(is_dup("http://example.org/", "http://example.org"))
+        self.assertTrue(is_dup("http://example.org", "http://example.org/"))
+        self.assertTrue(is_dup("http://example.org/index.html", "http://example.org"))
+        self.assertTrue(is_dup("http://example.org", "http://example.org/index.html"))
+        self.assertTrue(is_dup("http://example.org/index.htm", "http://example.org"))
+        self.assertTrue(is_dup("http://example.org", "http://example.org/index.htm"))