diff --git a/src/calibre/srv/auth.py b/src/calibre/srv/auth.py
index 2aecca45e3..c43348782c 100644
--- a/src/calibre/srv/auth.py
+++ b/src/calibre/srv/auth.py
@@ -11,7 +11,7 @@ from hashlib import md5, sha256
 from itertools import permutations
 from threading import Lock
 
-from calibre.srv.errors import HTTPAuthRequired, HTTPSimpleResponse, InvalidCredentials
+from calibre.srv.errors import HTTPAuthRequired, HTTPSimpleResponse
 from calibre.srv.http_request import parse_uri
 from calibre.srv.utils import parse_http_dict, encode_path
 from calibre.utils.monotonic import monotonic
@@ -196,13 +196,6 @@ class AuthController(object):
         self.realm = realm
         if '"' in realm:
             raise ValueError('Double-quotes are not allowed in the authentication realm')
-        for k, v in self.user_credentials.iteritems():
-            if '"' in k:
-                raise ValueError('Double-quotes are not allowed in usernames')
-            try:
-                k.encode('ascii'), v.encode('ascii')
-            except ValueError:
-                raise InvalidCredentials('Only ASCII characters are allowed in usernames and passwords')
 
     def check(self, un, pw):
         return pw and self.user_credentials.get(un) == pw
diff --git a/src/calibre/srv/errors.py b/src/calibre/srv/errors.py
index 42295f7c94..c53480fab2 100644
--- a/src/calibre/srv/errors.py
+++ b/src/calibre/srv/errors.py
@@ -43,6 +43,3 @@ class HTTPBadRequest(HTTPSimpleResponse):
 
     def __init__(self, message, close_connection=False):
         HTTPSimpleResponse.__init__(self, httplib.BAD_REQUEST, message, close_connection)
-
-class InvalidCredentials(ValueError):
-    pass
diff --git a/src/calibre/srv/standalone.py b/src/calibre/srv/standalone.py
index 9694108bdf..4741066f8f 100644
--- a/src/calibre/srv/standalone.py
+++ b/src/calibre/srv/standalone.py
@@ -10,7 +10,6 @@ import sys, os, signal
 
 from calibre import as_unicode, prints
 from calibre.constants import plugins, iswindows, preferred_encoding
-from calibre.srv.errors import InvalidCredentials
 from calibre.srv.loop import ServerLoop
 from calibre.srv.bonjour import BonJour
 from calibre.srv.opts import opts_to_parser
@@ -227,10 +226,7 @@ def main(args=sys.argv):
         except NoAutoReload as e:
             raise SystemExit(e.message)
     opts.auto_reload_port=int(os.environ.get('CALIBRE_AUTORELOAD_PORT', 0))
-    try:
-        server=Server(libraries, opts)
-    except InvalidCredentials as e:
-        raise SystemExit(e.message)
+    server=Server(libraries, opts)
     if opts.daemonize:
         if not opts.log and not iswindows:
             raise SystemExit('In order to daemonize you must specify a log file, you can use /dev/stdout to log to screen even as a daemon')