diff --git a/src/File/FileServer.py b/src/File/FileServer.py
index 21adebc09..ec947293a 100644
--- a/src/File/FileServer.py
+++ b/src/File/FileServer.py
@@ -5,6 +5,7 @@
 
 import gevent
 
+import util
 from Config import config
 from FileRequest import FileRequest
 from Site import SiteManager
@@ -165,7 +166,7 @@ def checkSite(self, site, check_files=True):
                 site.needConnections()
 
     # Check sites integrity
-    def checkSites(self):
+    @util.Noparallel()
     def checkSites(self, check_files=True):
         sites_checking = False
         if self.port_opened is None:  # Test and open port if not tested yet