diff --git a/core/net/rime/announcement.c b/core/net/rime/announcement.c
index 274c8f741..113d72d7c 100644
--- a/core/net/rime/announcement.c
+++ b/core/net/rime/announcement.c
@@ -33,7 +33,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: announcement.c,v 1.3 2010/02/23 18:32:44 adamdunkels Exp $
+ * $Id: announcement.c,v 1.4 2010/03/19 13:16:11 adamdunkels Exp $
  */
 
 /**
@@ -50,7 +50,7 @@
 LIST(announcements);
 
 static void (* listen_callback)(int time);
-static void (* observer_callback)(uint16_t id, uint16_t newval, uint16_t oldval);
+static announcement_observer observer_callback;
 
 /*---------------------------------------------------------------------------*/
 void
@@ -68,7 +68,7 @@ announcement_register(struct announcement *a, uint16_t id, uint16_t value,
   a->callback = callback;
   list_add(announcements, a);
   if(observer_callback) {
-    observer_callback(a->id, a->value, 0);
+    observer_callback(a->id, a->value, 0, ANNOUNCEMENT_BUMP);
   }
 }
 /*---------------------------------------------------------------------------*/
@@ -84,7 +84,7 @@ announcement_set_value(struct announcement *a, uint16_t value)
   uint16_t oldvalue = a->value;
   a->value = value;
   if(observer_callback) {
-    observer_callback(a->id, value, oldvalue);
+    observer_callback(a->id, value, oldvalue, ANNOUNCEMENT_NOBUMP);
   }
 }
 /*---------------------------------------------------------------------------*/
@@ -93,7 +93,15 @@ announcement_set_id(struct announcement *a, uint16_t id)
 {
   a->id = id;
   if(observer_callback) {
-    observer_callback(a->id, a->value, a->value);
+    observer_callback(a->id, a->value, a->value, ANNOUNCEMENT_NOBUMP);
+  }
+}
+/*---------------------------------------------------------------------------*/
+void
+announcement_bump(struct announcement *a)
+{
+  if(observer_callback) {
+    observer_callback(a->id, a->value, a->value, ANNOUNCEMENT_BUMP);
   }
 }
 /*---------------------------------------------------------------------------*/
@@ -112,7 +120,7 @@ announcement_register_listen_callback(void (*callback)(int time))
 }
 /*---------------------------------------------------------------------------*/
 void
-announcement_register_observer_callback(void (*callback)(uint16_t, uint16_t, uint16_t))
+announcement_register_observer_callback(announcement_observer callback)
 {
   observer_callback = callback;
 }
diff --git a/core/net/rime/announcement.h b/core/net/rime/announcement.h
index 279da58dd..ffca0d4d5 100644
--- a/core/net/rime/announcement.h
+++ b/core/net/rime/announcement.h
@@ -54,7 +54,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: announcement.h,v 1.6 2010/02/23 18:32:44 adamdunkels Exp $
+ * $Id: announcement.h,v 1.7 2010/03/19 13:16:11 adamdunkels Exp $
  */
 
 /**
@@ -153,6 +153,20 @@ void announcement_set_value(struct announcement *a, uint16_t value);
  */
 void announcement_set_id(struct announcement *a, uint16_t id);
 
+/**
+ * \brief      Bump an announcement
+ * \param a    A pointer to a struct announcement that has
+ *             previously been registered
+ *
+ *             This function is called to inform the announcement
+ *             module that a particular announcement has changed in a
+ *             way that it should be bumped. When an announcement is
+ *             bumped, the announcement back-end may send out a new
+ *             announcement to neighbors.
+ *
+ */
+void announcement_bump(struct announcement *a);
+
 /**
  * \brief      Listen for announcements for a specific amount of
  *             announcement periods
@@ -225,6 +239,14 @@ void announcement_heard(const rimeaddr_t *from, uint16_t id, uint16_t value);
  */
 void announcement_register_listen_callback(void (*callback)(int time));
 
+enum {
+  ANNOUNCEMENT_NOBUMP,
+  ANNOUNCEMENT_BUMP,
+};
+
+typedef void (* announcement_observer)(uint16_t id, uint16_t newvalue,
+                                       uint16_t oldvalue, uint8_t bump);
+
 /**
  * \brief      Register an observer callback with the announcement module
  * \param observer A pointer to an observer function
@@ -239,9 +261,7 @@ void announcement_register_listen_callback(void (*callback)(int time));
  *             message with the updated values.
  *
  */
-void announcement_register_observer_callback(void (*observer)(uint16_t id,
-							      uint16_t newvalue,
-                                                              uint16_t oldvalue));
+void announcement_register_observer_callback(announcement_observer observer);
 
 /**
  * @}