diff --git a/ChangeLog b/ChangeLog
index 119d33f1f..df6518426 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2012-03-16  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
 
+	* OpenChange/MAPIStoreTypes.m (MAPICNCompare): added as void *
+	parameter so that the function can be used as a comparator
+	function in NSArray sort methods.
+
 	* OpenChange/MAPIStoreMailFolder.m
 	(-getPidTagMessageClass:inMemCtx:): removed method, as folders are
 	not supposed to return a PidTagMessageClass attribute.
diff --git a/OpenChange/MAPIStoreGCSFolder.m b/OpenChange/MAPIStoreGCSFolder.m
index cf777ca3c..0464b5b97 100644
--- a/OpenChange/MAPIStoreGCSFolder.m
+++ b/OpenChange/MAPIStoreGCSFolder.m
@@ -631,11 +631,11 @@ static Class NSNumberK;
                   currentChangeNum
                     = [[messageEntry objectForKey: @"version"]
                         unsignedLongLongValue];
-                  if (MAPICNCompare (changeNum, currentChangeNum)
+                  if (MAPICNCompare (changeNum, currentChangeNum, NULL)
                       == NSOrderedAscending)
                     {
                       [(NSMutableArray *) deletedKeys addObject: cName];
-                      if (MAPICNCompare (maxChangeNum, currentChangeNum)
+                      if (MAPICNCompare (maxChangeNum, currentChangeNum, NULL)
                           == NSOrderedAscending)
                         maxChangeNum = currentChangeNum;
                     }
diff --git a/OpenChange/MAPIStoreTypes.h b/OpenChange/MAPIStoreTypes.h
index 5a8e3fb42..1fec6a6a7 100644
--- a/OpenChange/MAPIStoreTypes.h
+++ b/OpenChange/MAPIStoreTypes.h
@@ -42,7 +42,7 @@ id NSObjectFromSPropValue (const struct SPropValue *);
 id NSObjectFromMAPISPropValue (const struct mapi_SPropValue *);
 id NSObjectFromValuePointer (enum MAPITAGS, const void *);
 
-NSComparisonResult MAPICNCompare (uint64_t cn1, uint64_t cn2);
+NSComparisonResult MAPICNCompare (uint64_t cn1, uint64_t cn2, void *);
 NSComparisonResult MAPIChangeKeyGUIDCompare (NSData *ck1, NSData *ck2, void *);
 
 static inline NSNumber *
diff --git a/OpenChange/MAPIStoreTypes.m b/OpenChange/MAPIStoreTypes.m
index b7cd9bb98..c294dd429 100644
--- a/OpenChange/MAPIStoreTypes.m
+++ b/OpenChange/MAPIStoreTypes.m
@@ -284,7 +284,7 @@ _reverseCN (uint64_t cn)
 }
 
 NSComparisonResult
-MAPICNCompare (uint64_t cn1, uint64_t cn2)
+MAPICNCompare (uint64_t cn1, uint64_t cn2, void *unused)
 {
   NSComparisonResult result;