diff --git a/OpenChange/MAPIStoreGCSFolder.m b/OpenChange/MAPIStoreGCSFolder.m
index 750a255a4..52d2b0866 100644
--- a/OpenChange/MAPIStoreGCSFolder.m
+++ b/OpenChange/MAPIStoreGCSFolder.m
@@ -259,7 +259,6 @@ static Class NSNumberK;
   }
 }
  */
-
 - (void) _setChangeKey: (NSData *) changeKey
        forMessageEntry: (NSMutableDictionary *) messageEntry
       inChangeListOnly: (BOOL) inChangeListOnly
@@ -462,6 +461,9 @@ static Class NSNumberK;
               [messageEntry setObject: changeNumber forKey: @"version"];
 
               newChangeNum = [changeNumber unsignedLongLongValue];
+	      
+	      // A GLOBCNT structure is a 6-byte global namespace counter,
+	      // we strip the first 2 bytes. The first two bytes is the ReplicaId
               changeKey = [self getReplicaKeyFromGlobCnt: newChangeNum >> 16];
               [self _setChangeKey: changeKey forMessageEntry: messageEntry
                  inChangeListOnly: NO];
diff --git a/OpenChange/MAPIStoreObject.m b/OpenChange/MAPIStoreObject.m
index 7d4bb3219..1d468915c 100644
--- a/OpenChange/MAPIStoreObject.m
+++ b/OpenChange/MAPIStoreObject.m
@@ -284,6 +284,9 @@ static Class NSExceptionK, MAPIStoreFolderK;
   return MAPISTORE_SUCCESS;
 }
 
+//
+// The GlobCnt is 6 bytes long.
+//
 - (NSData *) getReplicaKeyFromGlobCnt: (uint64_t) objectCnt
 {
   struct mapistore_connection_info *connInfo;
diff --git a/OpenChange/NSData+MAPIStore.m b/OpenChange/NSData+MAPIStore.m
index b2bdedc97..44b6dcf85 100644
--- a/OpenChange/NSData+MAPIStore.m
+++ b/OpenChange/NSData+MAPIStore.m
@@ -148,6 +148,7 @@ static void _fillFlatUIDWithGUID (struct FlatUID_r *flatUID, const struct GUID *
 - (struct XID *) asXIDInMemCtx: (void *) memCtx
 {
   struct XID *xid;
+  uint8_t *bytes;
   NSUInteger max;
 
   max = [self length];
@@ -158,7 +159,9 @@ static void _fillFlatUIDWithGUID (struct FlatUID_r *flatUID, const struct GUID *
       [self _extractGUID: &xid->GUID];
 
       xid->Size = max - 16;
-      xid->Data = talloc_memdup (xid, [self bytes] + 16, xid->Size);
+
+      bytes = (uint8_t *) [self bytes];
+      xid->Data = talloc_memdup (xid, (bytes+16), xid->Size);
     }
   else
     {