diff --git a/src/mu-container.c b/src/mu-container.c
index cf4a6af4..d2b2f772 100644
--- a/src/mu-container.c
+++ b/src/mu-container.c
@@ -300,7 +300,7 @@ mu_container_from_list (GSList *lst)
 
 struct _SortFuncData {
 	MuMsgFieldId         mfid;
-	gboolean             invert;
+	gboolean             revert;
 	gpointer             user_data;
 };
 typedef struct _SortFuncData SortFuncData;
@@ -323,7 +323,7 @@ sort_func_wrapper (MuContainer *a, MuContainer *b, SortFuncData *data)
 	else if (!b1->msg)
 		return -1;
 
-	if (data->invert)
+	if (data->revert)
 		return mu_msg_cmp (b1->msg, a1->msg, data->mfid);
 	else
 		return mu_msg_cmp (a1->msg, b1->msg, data->mfid);
@@ -355,14 +355,14 @@ mu_container_sort_real (MuContainer *c, SortFuncData *sfdata)
 
 
 MuContainer*
-mu_container_sort (MuContainer *c, MuMsgFieldId mfid, gpointer user_data,
-		   gboolean invert)
+mu_container_sort (MuContainer *c, MuMsgFieldId mfid, gboolean revert,
+		   gpointer user_data)
 {
 
 	SortFuncData sfdata;
 
 	sfdata.mfid	 = mfid;
-	sfdata.invert	 = invert;
+	sfdata.revert	 = revert;
 	sfdata.user_data = user_data;
 
 	g_return_val_if_fail (c, NULL);
diff --git a/src/mu-container.h b/src/mu-container.h
index 1361c8a5..e3ddbe0d 100644
--- a/src/mu-container.h
+++ b/src/mu-container.h
@@ -34,7 +34,7 @@ typedef guint8 MuContainerFlag;
 
 /*
  * MuContainer data structure, as seen in JWZs document:
- *     http://www.jwz.org/doc/threading.html 
+ *     http://www.jwz.org/doc/threading.html
  */
 struct _MuContainer {
 	struct _MuContainer *parent, *child, *next;
@@ -48,11 +48,11 @@ typedef struct _MuContainer MuContainer;
 
 /**
  * create a new Container object
- * 
+ *
  * @param msg a MuMsg, or NULL; when it's NULL, docid should be 0
  * @param docid a Xapian docid, or 0
  * @param msgid a message id, or NULL
- * 
+ *
  * @return a new Container instance, or NULL in case of error; free
  * with mu_container_destroy
  */
@@ -61,7 +61,7 @@ MuContainer* mu_container_new (MuMsg *msg, guint docid, const char* msgid);
 
 /**
  * free a Container object
- * 
+ *
  * @param c a Container object, or NULL
  */
 void       mu_container_destroy (MuContainer *c);
@@ -71,10 +71,10 @@ void       mu_container_destroy (MuContainer *c);
 /**
  * append new child(ren) to this container; the child(ren) container's
  * parent pointer will point to this one
- * 
+ *
  * @param c a Container instance
  * @param child a child
- * 
+ *
  * @return the Container instance with a child added
  */
 MuContainer* mu_container_append_children (MuContainer *c, MuContainer *child);
@@ -82,20 +82,20 @@ MuContainer* mu_container_append_children (MuContainer *c, MuContainer *child);
 /**
  * append a new sibling to this (list of) containers; all the siblings
  * will get the same parent that @c has
- * 
+ *
  * @param c a container instance
- * @param sibling a sibling 
- * 
+ * @param sibling a sibling
+ *
  * @return the container (list) with the sibling(s) appended
  */
 MuContainer* mu_container_append_siblings (MuContainer *c, MuContainer *sibling);
 
 /**
  * remove a _single_ child container from a container
- * 
+ *
  * @param c a container instance
  * @param child the child container to remove
- * 
+ *
  * @return the container with the child removed; if the container did
  * have this child, nothing changes
  */
@@ -103,10 +103,10 @@ MuContainer* mu_container_remove_child (MuContainer *c, MuContainer *child);
 
 /**
  * remove a _single_ sibling container from a container
- * 
+ *
  * @param c a container instance
  * @param sibling the sibling container to remove
- * 
+ *
  * @return the container with the sibling removed; if the container did
  * have this sibling, nothing changes
  */
@@ -115,10 +115,10 @@ MuContainer* mu_container_remove_sibling (MuContainer *c, MuContainer *sibling);
 
 /**
  * promote child's children to be parent's children and remove child
- * 
+ *
  * @param parent a container instance
  * @param child a child of this container
- * 
+ *
  * @return the new container with it's children's children promoted
  */
 MuContainer* mu_container_splice_children (MuContainer *parent,
@@ -130,12 +130,12 @@ typedef gboolean (*MuContainerForeachFunc) (MuContainer*, gpointer);
  * execute some function on all siblings an children of some container
  * (recursively) until all children have been visited or the callback
  * function returns FALSE
- * 
+ *
  * @param c a container
  * @param func a function to call for each container
  * @param user_data a pointer to pass to the callback function
- * 
- * @return 
+ *
+ * @return
  */
 gboolean   mu_container_foreach (MuContainer *c,
 				 MuContainerForeachFunc func,
@@ -144,10 +144,10 @@ gboolean   mu_container_foreach (MuContainer *c,
 /**
  * check wither container needle is a child or sibling (recursively)
  * of container haystack
- * 
+ *
  * @param haystack a container
  * @param needle a container
- * 
+ *
  * @return TRUE if needle is reachable from haystack, FALSE otherwise
  */
 gboolean   mu_container_reachable (MuContainer *haystack, MuContainer *needle);
@@ -155,8 +155,8 @@ gboolean   mu_container_reachable (MuContainer *haystack, MuContainer *needle);
 
 /**
  * dump the container to stdout (for debugging)
- * 
- * @param c a container 
+ *
+ * @param c a container
  * @param recursive whether to include siblings, children
  */
 void       mu_container_dump (MuContainer *c, gboolean recursive);
@@ -169,26 +169,26 @@ typedef int (*MuContainerCmpFunc) (MuContainer *c1, MuContainer *c2,
  * sort the tree of MuContainers, recursively; ie. each of the list of
  * siblings (children) will be sorted according to @func; if the
  * container is empty, the first non-empty 'leftmost' child is used.
- * 
+ *
  * @param c a container
  * @param mfid the field to sort by
+ * @param revert if TRUE, revert the sorting order *
  * @param user_data a user pointer to pass to the sorting function
- * @param invert if TRUE, invert the sorting order
- * 
+ *
  * @return a sorted container
  */
-MuContainer* mu_container_sort (MuContainer *c, MuMsgFieldId mfid,
-				gpointer user_data, gboolean invert);
+MuContainer* mu_container_sort (MuContainer *c, MuMsgFieldId mfid, gboolean revert,
+				gpointer user_data);
 
 
 /**
  * create a hashtable with maps document-ids to information about them,
  * ie. Xapian docid => MuMsgIterThreadInfo
- * 
+ *
  * @param root_set the containers @param matchnum the number of
  * matches in the list (this is needed to determine the shortest
  * possible collation keys ('threadpaths') for the messages
- * 
+ *
  * @return a hash; free with g_hash_table_destroy
  */
 GHashTable* mu_container_thread_info_hash_new (MuContainer *root_set,
diff --git a/src/mu-threader.c b/src/mu-threader.c
index ff2c0a1f..2876de45 100644
--- a/src/mu-threader.c
+++ b/src/mu-threader.c
@@ -58,7 +58,8 @@ GHashTable* create_doc_id_thread_path_hash (MuContainer *root, size_t match_num)
 /* msg threading algorithm, based on JWZ's algorithm,
  * http://www.jwz.org/doc/threading.html */
 GHashTable*
-mu_threader_calculate (MuMsgIter *iter, size_t matchnum, MuMsgFieldId sortfield)
+mu_threader_calculate (MuMsgIter *iter, size_t matchnum,
+		       MuMsgFieldId sortfield, gboolean revert)
 {
 	GHashTable *id_table, *thread_ids;
 	MuContainer *root_set;
@@ -81,8 +82,8 @@ mu_threader_calculate (MuMsgIter *iter, size_t matchnum, MuMsgFieldId sortfield)
 
 	/* sort root set */
 	if (sortfield != MU_MSG_FIELD_ID_NONE)
-		root_set = mu_container_sort (root_set, sortfield,
-					      NULL, FALSE);
+		root_set = mu_container_sort (root_set, sortfield, revert,
+					      NULL);
 
 	/* step 5: group root set by subject */
 	/* group_root_set_by_subject (root_set); */
diff --git a/src/mu-threader.h b/src/mu-threader.h
index 9e0d1af1..2ee0e0af 100644
--- a/src/mu-threader.h
+++ b/src/mu-threader.h
@@ -43,11 +43,12 @@ G_BEGIN_DECLS
  * @param matches the number of matches in the set *
  * @param sortfield the field to sort results by, or
  * MU_MSG_FIELD_ID_NONE if no sorting should be performed
- * 
+ * @param revert if TRUE, if revert the sorting order
+ *
  * @return a hashtable; free with g_hash_table_destroy when done with it
- */	
+ */
 GHashTable *mu_threader_calculate (MuMsgIter *iter, size_t matches,
-				   MuMsgFieldId sortfield);
+				   MuMsgFieldId sortfield, gboolean revert);
 
 
 G_END_DECLS