diff --git a/src/calibre/ebooks/conversion/plugins/html_input.py b/src/calibre/ebooks/conversion/plugins/html_input.py
index 9f257516d9..c1ee9ffd9e 100644
--- a/src/calibre/ebooks/conversion/plugins/html_input.py
+++ b/src/calibre/ebooks/conversion/plugins/html_input.py
@@ -291,7 +291,7 @@ class HTMLInput(InputFormatPlugin):
             # file, therefore we quote it here.
             if isinstance(bhref, unicode_type):
                 bhref = bhref.encode('utf-8')
-            item.html_input_href = quote(bhref).decode('utf-8')
+            item.html_input_href = unicode_type(quote(bhref))
             if guessed in self.OEB_STYLES:
                 item.override_css_fetch = partial(
                         self.css_import_handler, os.path.dirname(link))
diff --git a/src/calibre/ebooks/metadata/sources/identify.py b/src/calibre/ebooks/metadata/sources/identify.py
index 57d032cb92..2259d80567 100644
--- a/src/calibre/ebooks/metadata/sources/identify.py
+++ b/src/calibre/ebooks/metadata/sources/identify.py
@@ -554,7 +554,7 @@ def urls_from_identifiers(identifiers):  # {{{
         formatter = EvalFormatter()
         for k, val in iteritems(identifiers):
             val = val.replace('|', ',')
-            vals = {'id':quote(val if isinstance(val, bytes) else val.encode('utf-8')).decode('ascii')}
+            vals = {'id':unicode_type(quote(val if isinstance(val, bytes) else val.encode('utf-8')))}
             items = rules.get(k) or ()
             for name, template in items:
                 try:
diff --git a/src/calibre/srv/routes.py b/src/calibre/srv/routes.py
index ca3bb68166..1e092a9d1d 100644
--- a/src/calibre/srv/routes.py
+++ b/src/calibre/srv/routes.py
@@ -89,7 +89,7 @@ def endpoint(route,
         f.ok_code = ok_code
         f.is_endpoint = True
         f.needs_db_write = needs_db_write
-        argspec = inspect.getargspec(f)
+        argspec = inspect.getfullargspec(f) if ispy3 else inspect.getargspec(f)
         if len(argspec.args) < 2:
             raise TypeError('The endpoint %r must take at least two arguments' % f.route)
         f.__annotations__ = {
diff --git a/src/calibre/srv/tests/ajax.py b/src/calibre/srv/tests/ajax.py
index 36c343adc9..915eae11de 100644
--- a/src/calibre/srv/tests/ajax.py
+++ b/src/calibre/srv/tests/ajax.py
@@ -111,8 +111,8 @@ class ContentTest(LibraryBaseTest):
                 r, data = make_request(conn, path, username='12', password='test', prefix='', method=method)
                 ae(status, r.status)
                 if status == NOT_FOUND:
-                    p = data.partition(':')[0]
-                    ae(p, 'No book with id')
+                    p = data.partition(b':')[0]
+                    ae(p, b'No book with id')
                 return data
             ok = r
             nf = partial(r, status=NOT_FOUND)
diff --git a/src/calibre/srv/tests/loop.py b/src/calibre/srv/tests/loop.py
index 9543678d77..bf59cf7537 100644
--- a/src/calibre/srv/tests/loop.py
+++ b/src/calibre/srv/tests/loop.py
@@ -134,7 +134,7 @@ class LoopTest(BaseTest):
 
     def test_dual_stack(self):
         from calibre.srv.loop import IPPROTO_IPV6
-        with TestServer(lambda data:(data.path[0] + data.read()), listen_on='::') as server:
+        with TestServer(lambda data:(data.path[0] + data.read().decode('utf-8')), listen_on='::') as server:
             self.ae(server.address[0], '::')
             self.ae(server.loop.socket.getsockopt(IPPROTO_IPV6, socket.IPV6_V6ONLY), 0)
             conn = server.connect(interface='127.0.0.1')
diff --git a/src/calibre/srv/tests/web_sockets.py b/src/calibre/srv/tests/web_sockets.py
index 062b2cfcff..63a733511a 100644
--- a/src/calibre/srv/tests/web_sockets.py
+++ b/src/calibre/srv/tests/web_sockets.py
@@ -64,9 +64,10 @@ class WSClient(object):
         if rl != b'HTTP/1.1 101 Switching Protocols\r\n':
             raise ValueError('Server did not respond with correct switching protocols line')
         headers = read_headers(partial(next, lines))
-        key = as_base64_unicode(sha1(self.key + GUID_STR).digest())
+        key = as_base64_unicode(sha1(self.key + GUID_STR.encode('ascii')).digest())
         if headers.get('Sec-WebSocket-Accept') != key:
-            raise ValueError('Server did not respond with correct key in Sec-WebSocket-Accept')
+            raise ValueError('Server did not respond with correct key in Sec-WebSocket-Accept: {} != {}'.format(
+                key, headers.get('Sec-WebSocket-Accept')))
 
     def recv(self, max_amt):
         if self.read_buf:
diff --git a/src/calibre/utils/linux_trash.py b/src/calibre/utils/linux_trash.py
index 8ab56eaa5f..32a4ac30e8 100644
--- a/src/calibre/utils/linux_trash.py
+++ b/src/calibre/utils/linux_trash.py
@@ -42,7 +42,7 @@ TOPDIR_FALLBACK = '.Trash-%s'%uid
 def uniquote(raw):
     if isinstance(raw, unicode_type):
         raw = raw.encode('utf-8')
-    return quote(raw).decode('utf-8')
+    return unicode_type(quote(raw))
 
 
 def is_parent(parent, path):