diff --git a/ChangeLog b/ChangeLog
index 7414eb7a4..8ca0bbb9e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2011-09-23  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
 
+	* OpenChange/MAPIStoreGCSMessage.m (-getPrChangeKey:inMemCtx:):
+	first force a synchronisation of the parent cache if the change key
+	cannot be retrieved and invoke abort if the change key is still
+	not available afterwards.
+
+	* OpenChange/MAPIStoreMailMessage.m (-getPrChangeKey:inMemCtx:):
+	same as above.
+
 	* OpenChange/MAPIStoreMailFolder.m (-lastMessageModificationTime):
 	invoke "synchroniseCache" in order to make sure we return the real
 	last modification time.
diff --git a/OpenChange/MAPIStoreGCSMessage.m b/OpenChange/MAPIStoreGCSMessage.m
index ac4babe3f..0f7828adc 100644
--- a/OpenChange/MAPIStoreGCSMessage.m
+++ b/OpenChange/MAPIStoreGCSMessage.m
@@ -52,13 +52,21 @@
 {
   int rc = MAPISTORE_SUCCESS;
   NSData *changeKey;
+  MAPIStoreGCSFolder *parentFolder;
+  NSString *nameInContainer;
 
   if (isNew)
     rc = MAPISTORE_ERR_NOT_FOUND;
   else
     {
-      changeKey = [(MAPIStoreGCSFolder *)[self container]
-                      changeKeyForMessageWithKey: [self nameInContainer]];
+      parentFolder = (MAPIStoreGCSFolder *)[self container];
+      nameInContainer = [self nameInContainer];
+      changeKey = [parentFolder changeKeyForMessageWithKey: nameInContainer];
+      if (!changeKey)
+        {
+          [parentFolder synchroniseCache];
+          changeKey = [parentFolder changeKeyForMessageWithKey: nameInContainer];
+        }
       if (!changeKey)
         abort ();
       *data = [changeKey asBinaryInMemCtx: memCtx];
diff --git a/OpenChange/MAPIStoreMailMessage.m b/OpenChange/MAPIStoreMailMessage.m
index 3fba97852..57cd1af34 100644
--- a/OpenChange/MAPIStoreMailMessage.m
+++ b/OpenChange/MAPIStoreMailMessage.m
@@ -284,13 +284,21 @@ _compareBodyKeysByPriority (id entry1, id entry2, void *data)
 {
   int rc = MAPISTORE_SUCCESS;
   NSData *changeKey;
+  MAPIStoreMailFolder *parentFolder;
+  NSString *nameInContainer;
 
   if (isNew)
     rc = MAPISTORE_ERR_NOT_FOUND;
   else
     {
-      changeKey = [(MAPIStoreMailFolder *)[self container]
-                      changeKeyForMessageWithKey: [self nameInContainer]];
+      parentFolder = (MAPIStoreMailFolder *)[self container];
+      nameInContainer = [self nameInContainer];
+      changeKey = [parentFolder changeKeyForMessageWithKey: nameInContainer];
+      if (!changeKey)
+        {
+          [parentFolder synchroniseCache];
+          changeKey = [parentFolder changeKeyForMessageWithKey: nameInContainer];
+        }
       if (!changeKey)
         abort ();
       *data = [changeKey asBinaryInMemCtx: memCtx];