diff --git a/openbis-ipad/BisKit/Classes/CISDOBIpadServiceManager.h b/openbis-ipad/BisKit/Classes/CISDOBIpadServiceManager.h
index d6d4a095b739c252736f136c7727bbf007a17786..00ab1fa6f7c71919d98f594cb923fa2cf22de83b 100644
--- a/openbis-ipad/BisKit/Classes/CISDOBIpadServiceManager.h
+++ b/openbis-ipad/BisKit/Classes/CISDOBIpadServiceManager.h
@@ -36,6 +36,7 @@
 @property (readonly, strong) NSManagedObjectModel *managedObjectModel;
 @property (readonly, strong) NSPersistentStoreCoordinator *persistentStoreCoordinator;
 @property (readonly, strong) NSEntityDescription *ipadEntityDescription;
+@property (readonly, strong) NSOperationQueue *queue;
 
 
 // Initialization
diff --git a/openbis-ipad/BisKit/Classes/CISDOBIpadServiceManager.m b/openbis-ipad/BisKit/Classes/CISDOBIpadServiceManager.m
index 57dcfe2672a0f7d65623c38042173d0e6e48419e..a65d243590e80768aa0136b741574f76d8069af3 100644
--- a/openbis-ipad/BisKit/Classes/CISDOBIpadServiceManager.m
+++ b/openbis-ipad/BisKit/Classes/CISDOBIpadServiceManager.m
@@ -99,6 +99,8 @@ static NSManagedObjectContext* GetMainThreadManagedObjectContext(NSURL* storeUrl
     _ipadEntityDescription = [NSEntityDescription entityForName: @"CISDOBIpadEntity" inManagedObjectContext: _managedObjectContext];
     _managedObjectModel = [_ipadEntityDescription managedObjectModel];
     
+    _queue = [[NSOperationQueue alloc] init];
+    
     return self;
 }
 
@@ -110,8 +112,7 @@ static NSManagedObjectContext* GetMainThreadManagedObjectContext(NSURL* storeUrl
         [synchronizer run];
         [synchronizer performSelectorOnMainThread: @selector(notifyCallOfResult:) withObject: nil waitUntilDone: NO];
     };
-    NSBlockOperation *blockOp = [NSBlockOperation blockOperationWithBlock:  syncBlock];
-    [blockOp start];
+    [_queue addOperationWithBlock: syncBlock];
 }
 
 - (CISDOBIpadServiceManagerCall *)managerCallWrappingServiceCall:(CISDOBAsyncCall *)serviceCall pruning:(BOOL)prune