diff --git a/django/contrib/comments/views/utils.py b/django/contrib/comments/views/utils.py
index a37c555e78..c5c900d47f 100644
--- a/django/contrib/comments/views/utils.py
+++ b/django/contrib/comments/views/utils.py
@@ -25,7 +25,8 @@ def next_redirect(data, default, default_view, **get_kwargs):
     if next is None:
         next = urlresolvers.reverse(default_view)
     if get_kwargs:
-        next += "?" + urllib.urlencode(get_kwargs)
+        joiner = ('?' in next) and '&' or '?'
+        next += joiner + urllib.urlencode(get_kwargs)
     return HttpResponseRedirect(next)
 
 def confirmation_view(template, doc="Display a confirmation view."):
diff --git a/tests/regressiontests/comment_tests/tests/comment_view_tests.py b/tests/regressiontests/comment_tests/tests/comment_view_tests.py
index 312fab633f..192131bf0c 100644
--- a/tests/regressiontests/comment_tests/tests/comment_view_tests.py
+++ b/tests/regressiontests/comment_tests/tests/comment_view_tests.py
@@ -207,3 +207,16 @@ class CommentViewTests(CommentTestCase):
         self.assertTemplateUsed(response, "comments/posted.html")
         self.assertEqual(response.context[0]["comment"], Comment.objects.get(pk=pk))
 
+    def testCommentNextWithQueryString(self):
+        """
+        The `next` key needs to handle already having a query string (#10585)
+        """
+        a = Article.objects.get(pk=1)
+        data = self.getValidData(a)
+        data["next"] = "/somewhere/else/?foo=bar"
+        data["comment"] = "This is another comment"
+        response = self.client.post("/post/", data)
+        location = response["Location"]        
+        match = re.search(r"^http://testserver/somewhere/else/\?foo=bar&c=\d+$", location)
+        self.failUnless(match != None, "Unexpected redirect location: %s" % location)
+        
\ No newline at end of file