diff --git a/scrapy/trunk/scrapy/tests/test_utils_url.py b/scrapy/trunk/scrapy/tests/test_utils_url.py
index da30f501d..9d8709511 100644
--- a/scrapy/trunk/scrapy/tests/test_utils_url.py
+++ b/scrapy/trunk/scrapy/tests/test_utils_url.py
@@ -149,12 +149,18 @@ class UrlUtilsTest(unittest.TestCase):
                                           u"http://user:pass@www.example.com/do?a=1#frag")
 
     def test_check_valid_urlencode(self):
-        self.assertFalse(check_valid_urlencode(r'http://www.example.com/pictures detail CAN43664.jpg'))
-        self.assertTrue(check_valid_urlencode('http://www.example.com/pictures%20detail%20CAN43664.jpg'))
-
         self.assertFalse(check_valid_urlencode(r'http://www.example.com/pictures\detail\CAN43664.jpg'))
         self.assertTrue(check_valid_urlencode('http://www.example.com/pictures%5Cdetail%5CCAN43664.jpg'))
 
+        self.assertFalse(check_valid_urlencode('http://www.example.com/pictures detail CAN43664.jpg'))
+        self.assertTrue(check_valid_urlencode('http://www.example.com/pictures+detail%20CAN43664.jpg'))
+
+        self.assertFalse(check_valid_urlencode('http://www.example.com/?q=foo bar&q2=foo2 bar2'))
+        self.assertTrue(check_valid_urlencode('http://www.example.com/?q=foo+bar&q2=foo2%20bar2'))
+
+        self.assertFalse(check_valid_urlencode('http://www.example.com/product,little:london$set%'))
+        self.assertTrue(check_valid_urlencode('http://www.example.com/product%2Clittle%3Alondon%24set%25'))
+
 if __name__ == "__main__":
     unittest.main()
 
diff --git a/scrapy/trunk/scrapy/utils/url.py b/scrapy/trunk/scrapy/utils/url.py
index f75348c6c..b989f1941 100644
--- a/scrapy/trunk/scrapy/utils/url.py
+++ b/scrapy/trunk/scrapy/utils/url.py
@@ -148,7 +148,11 @@ def canonicalize_url(url, keep_blank_values=False, keep_fragments=False):
     return urlparse.urlunparse(parts)
 
 def check_valid_urlencode(url):
-    """ check that the url-path is properly quoted
-    TODO should also check the parameters """
+    """ check that the url-path and arguments are properly quoted """
+    def check_str(s):
+        return all((s_plus == urllib.quote(urllib.unquote(s_plus)) for s_plus in s.split('+')))
+    def check_param(p):
+        return all((check_str(s) for s in p.split('=', 1)))
+
     split_result = urlparse.urlsplit(url)
-    return split_result[2] == urllib.quote(urllib.unquote(split_result[2]))
+    return check_str(split_result[2]) and all((check_param(p) for p in split_result[3].split('&')))