diff --git a/tests/test_url.py b/tests/test_url.py
index 3c9499aa..e821ec31 100644
--- a/tests/test_url.py
+++ b/tests/test_url.py
@@ -4,7 +4,7 @@
 import unittest
 from w3lib.url import (safe_url_string, safe_download_url,
     url_query_parameter, add_or_replace_parameter, url_query_cleaner,
-    file_uri_to_path, path_to_file_uri, any_to_uri)
+    file_uri_to_path, path_to_file_uri, any_to_uri, urljoin_rfc)
 
 class UrlTests(unittest.TestCase):
 
@@ -315,6 +315,10 @@ def test_any_to_uri(self):
         self.assertEqual(any_to_uri("http://www.example.com/some/path.txt"),
                          "http://www.example.com/some/path.txt")
 
+    def test_urljoin_rfc_deprecated(self):
+        jurl = urljoin_rfc("http://www.example.com/", "/test")
+        self.assertEqual(jurl, b"http://www.example.com/test")
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/w3lib/url.py b/w3lib/url.py
index 56c0a950..6c09d79a 100644
--- a/w3lib/url.py
+++ b/w3lib/url.py
@@ -57,8 +57,8 @@ def urljoin_rfc(base, ref, encoding='utf-8'):
     warnings.warn("w3lib.url.urljoin_rfc is deprecated, use urlparse.urljoin instead",
         DeprecationWarning)
 
-    str_base = unicode_to_str(base, encoding)
-    str_ref = unicode_to_str(ref, encoding)
+    str_base = to_bytes(base, encoding)
+    str_ref = to_bytes(ref, encoding)
     return urljoin(str_base, str_ref)
 
 _reserved = b';/?:@&=+$|,#' # RFC 3986 (Generic Syntax)