diff --git a/lastfm/__init__.py b/lastfm/__init__.py
index edabba8..bb84046 100644
--- a/lastfm/__init__.py
+++ b/lastfm/__init__.py
@@ -13,7 +13,7 @@ __package__ = "lastfm"
 
 import sys
 import os
-sys.path.append(os.path.dirname(os.path.dirname(__file__)))
+sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
 from lastfm.album import Album
 from lastfm.api import Api
diff --git a/lastfm/api.py b/lastfm/api.py
index bec7b84..ffb6177 100644
--- a/lastfm/api.py
+++ b/lastfm/api.py
@@ -64,6 +64,7 @@ class Api(object):
         self._no_cache = no_cache
         self._debug = debug
         self._last_fetch_time = datetime.now()
+        self._lock = Lock()
 
     @property
     def api_key(self):
@@ -643,13 +644,14 @@ class Api(object):
             return urllib.urlencode([(k, self._encode(parameters[k])) for k in keys if parameters[k] is not None])
 
     def _read_url_data(self, opener, url, data = None):
-        now = datetime.now()
-        delta = now - self._last_fetch_time
-        delta = delta.seconds + float(delta.microseconds)/1000000
-        if delta < Api.FETCH_INTERVAL:
-            time.sleep(Api.FETCH_INTERVAL - delta)
-        url_data = opener.open(url, data).read()
-        self._last_fetch_time = datetime.now()
+        with self._lock:
+            now = datetime.now()
+            delta = now - self._last_fetch_time
+            delta = delta.seconds + float(delta.microseconds)/1000000
+            if delta < Api.FETCH_INTERVAL:
+                time.sleep(Api.FETCH_INTERVAL - delta)
+            url_data = opener.open(url, data).read()
+            self._last_fetch_time = datetime.now()
         return url_data
 
     def _fetch_url(self,
@@ -765,6 +767,7 @@ class Api(object):
         return "<lastfm.Api: %s>" % self._api_key
 
 from datetime import datetime
+from threading import Lock
 import sys
 import time
 import urllib
diff --git a/lastfm/decorators.py b/lastfm/decorators.py
index 2997586..9da9aa3 100644
--- a/lastfm/decorators.py
+++ b/lastfm/decorators.py
@@ -60,7 +60,7 @@ def cached_property(func):
     return property(fget = wrapper, doc = func.__doc__)
 
 @decorator
-def authenticate(func, *args, **kwargs):
+def authentication_required(func, *args, **kwargs):
     """
     A decorator to check if the current user is authenticated or not. Used only
     on the functions that need authentication. If not authenticated then an
diff --git a/lastfm/mixins/taggable.py b/lastfm/mixins/taggable.py
index f23a313..a8aab89 100644
--- a/lastfm/mixins/taggable.py
+++ b/lastfm/mixins/taggable.py
@@ -6,14 +6,14 @@ __license__ = "GNU Lesser General Public License"
 __package__ = "lastfm.mixins"
 
 from lastfm.safelist import SafeList
-from lastfm.decorators import cached_property, authenticate
+from lastfm.decorators import cached_property, authentication_required
 
 class Taggable(object):
     def init(self, api):
         self._api = api
         
     @cached_property
-    @authenticate
+    @authentication_required
     def tags(self):
         from lastfm.tag import Tag
         params = self._default_params({'method': '%s.getTags' % self.__class__.__name__.lower()})
@@ -28,7 +28,7 @@ class Taggable(object):
                        ],
                        self.add_tags, self.remove_tag)
     
-    @authenticate
+    @authentication_required
     def add_tags(self, tags):
         from lastfm.tag import Tag
         while(len(tags) > 10):
@@ -52,7 +52,7 @@ class Taggable(object):
         self._api._post_data(params)
         self._tags = None
         
-    @authenticate
+    @authentication_required
     def remove_tag(self, tag):
         from lastfm.tag import Tag
         if isinstance(tag, Tag):