diff --git a/requests/models.py b/requests/models.py
index 03ff627a..bbf08c81 100644
--- a/requests/models.py
+++ b/requests/models.py
@@ -334,7 +334,9 @@ class PreparedRequest(RequestEncodingMixin, RequestHooksMixin):
         except UnicodeDecodeError:
             pass
 
-        # Don't do any URL preparation for oddball schemes
+        # Don't do any URL preparation for non-HTTP schemes like `mailto`,
+        # `data` etc to work around exceptions from `url_parse`, which
+        # handles RFC 3986 only.
         if ':' in url and not url.lower().startswith('http'):
             self.url = url
             return
diff --git a/test_requests.py b/test_requests.py
index 9f75a9d9..4fccc346 100755
--- a/test_requests.py
+++ b/test_requests.py
@@ -922,7 +922,7 @@ class RequestsTestCase(unittest.TestCase):
 
         assert p.headers['Content-Length'] == length
 
-    def test_oddball_schemes_dont_check_URLs(self):
+    def test_nonhttp_schemes_dont_check_URLs(self):
         test_urls = (
             'data:image/gif;base64,R0lGODlhAQABAHAAACH5BAUAAAAALAAAAAABAAEAAAICRAEAOw==',
             'file:///etc/passwd',