diff --git a/src/calibre/web/fetch/simple.py b/src/calibre/web/fetch/simple.py
index 971f52a4e5..ca81b139e4 100644
--- a/src/calibre/web/fetch/simple.py
+++ b/src/calibre/web/fetch/simple.py
@@ -103,7 +103,7 @@ def save_soup(soup, target):
         f.write(html.encode('utf-8'))
 
 
-class response(str):
+class response(bytes):
 
     def __new__(cls, *args):
         obj = super(response, cls).__new__(cls, *args)
@@ -261,16 +261,13 @@ class RecursiveFetcher(object):
         delta = time.time() - self.last_fetch_at
         if delta < self.delay:
             time.sleep(self.delay - delta)
-        if isinstance(url, unicode_type):
-            url = url.encode('utf-8')
-        # Not sure is this is really needed as I think mechanize
-        # handles quoting automatically, but leaving it
-        # in case it breaks something
+        # mechanize does not handle quoting automatically
         if re.search(r'\s+', url) is not None:
+            url = url.encode('utf-8')
             purl = list(urlparse(url))
             for i in range(2, 6):
                 purl[i] = quote(purl[i])
-            url = urlunparse(purl)
+            url = urlunparse(purl).decode('utf-8')
         open_func = getattr(self.browser, 'open_novisit', self.browser.open)
         try:
             with closing(open_func(url, timeout=self.timeout)) as f:
@@ -414,8 +411,6 @@ class RecursiveFetcher(object):
                     continue
             c += 1
             fname = ascii_filename('img'+str(c))
-            if isinstance(fname, unicode_type):
-                fname = fname.encode('ascii', 'replace')
             data = self.preprocess_image_ext(data, iurl) if self.preprocess_image_ext is not None else data
             if data is None:
                 continue
@@ -520,7 +515,7 @@ class RecursiveFetcher(object):
                     dsrc = self.fetch_url(iurl)
                     newbaseurl = dsrc.newurl
                     if len(dsrc) == 0 or \
-                       len(re.compile('<!--.*?-->', re.DOTALL).sub('', dsrc).strip()) == 0:
+                       len(re.compile(b'<!--.*?-->', re.DOTALL).sub(b'', dsrc).strip()) == 0:
                         raise ValueError('No content at URL %r'%iurl)
                     if callable(self.encoding):
                         dsrc = self.encoding(dsrc)
@@ -544,7 +539,7 @@ class RecursiveFetcher(object):
                     _fname = basename(iurl)
                     if not isinstance(_fname, unicode_type):
                         _fname.decode('latin1', 'replace')
-                    _fname = _fname.encode('ascii', 'replace').replace('%', '').replace(os.sep, '')
+                    _fname = _fname.replace('%', '').replace(os.sep, '').encode('ascii', 'replace')
                     _fname = ascii_filename(_fname)
                     _fname = os.path.splitext(_fname)[0][:120] + '.xhtml'
                     res = os.path.join(linkdiskpath, _fname)