diff -ur dhcp-4.2.4-P1/server/dhcpv6.c dhcp-4.2.4-P2/server/dhcpv6.c
--- dhcp-4.2.4-P1/server/dhcpv6.c	2012-07-13 02:18:05.000000000 -0400
+++ dhcp-4.2.4-P2/server/dhcpv6.c	2012-08-27 22:13:22.000000000 -0400
@@ -1837,9 +1837,6 @@
 			ia_reference(&tmp->ia, reply->ia, MDL);
 
 			/* Commit 'hard' bindings. */
-			tmp->hard_lifetime_end_time =
-				tmp->soft_lifetime_end_time;
-			tmp->soft_lifetime_end_time = 0;
 			renew_lease6(tmp->ipv6_pool, tmp);
 			schedule_lease_timeout(tmp->ipv6_pool);
 
@@ -2498,9 +2495,6 @@
 			ia_reference(&tmp->ia, reply->ia, MDL);
 
 			/* Commit 'hard' bindings. */
-			tmp->hard_lifetime_end_time =
-				tmp->soft_lifetime_end_time;
-			tmp->soft_lifetime_end_time = 0;
 			renew_lease6(tmp->ipv6_pool, tmp);
 			schedule_lease_timeout(tmp->ipv6_pool);
 
@@ -3370,9 +3364,6 @@
 			ia_reference(&tmp->ia, reply->ia, MDL);
 
 			/* Commit 'hard' bindings. */
-			tmp->hard_lifetime_end_time =
-				tmp->soft_lifetime_end_time;
-			tmp->soft_lifetime_end_time = 0;
 			renew_lease6(tmp->ipv6_pool, tmp);
 			schedule_lease_timeout(tmp->ipv6_pool);
 		}
diff -ur dhcp-4.2.4-P1/server/mdb6.c dhcp-4.2.4-P2/server/mdb6.c
--- dhcp-4.2.4-P1/server/mdb6.c	2012-07-13 02:17:54.000000000 -0400
+++ dhcp-4.2.4-P2/server/mdb6.c	2012-08-27 22:13:22.000000000 -0400
@@ -1235,29 +1238,49 @@
 	return insert_result;
 }
 
-/*
- * Renew an lease in the pool.
+/*!
+ * \brief Renew a lease in the pool.
+ *
+ * The hard_lifetime_end_time of the lease should be set to
+ * the current expiration time.
+ * The soft_lifetime_end_time of the lease should be set to
+ * the desired expiration time.
+ *
+ * This routine will compare the two and call the correct
+ * heap routine to move the lease.  If the lease is active
+ * and the new expiration time is greater (the normal case)
+ * then we call isc_heap_decreased() as a larger time is a
+ * lower priority.  If the new expiration time is less then
+ * we call isc_heap_increased().
+ *
+ * If the lease is abandoned then it will be on the active list
+ * and we will always call isc_heap_increased() as the previous
+ * expiration would have been all 1s (as close as we can get
+ * to infinite).
+ *
+ * If the lease is moving to active we call that routine
+ * which will move it from the inactive list to the active list.
  *
- * To do this, first set the new hard_lifetime_end_time for the resource,
- * and then invoke renew_lease6() on it.
+ * \param pool a pool the lease belongs to
+ * \param lease the lease to be renewed
  *
- * WARNING: lease times must only be extended, never reduced!!!
+ * \return result of the renew operation (ISC_R_SUCCESS if successful,
+           ISC_R_NOMEMORY when run out of memory)
  */
 isc_result_t
 renew_lease6(struct ipv6_pool *pool, struct iasubopt *lease) {
-	/*
-	 * If we're already active, then we can just move our expiration
-	 * time down the heap. 
-	 *
-	 * If we're abandoned then we are already on the active list
-	 * but we need to retag the lease and move our expiration
-	 * from infinite to the current value
-	 *
-	 * Otherwise, we have to move from the inactive heap to the 
-	 * active heap.
-	 */
+	time_t old_end_time = lease->hard_lifetime_end_time;
+	lease->hard_lifetime_end_time = lease->soft_lifetime_end_time;
+	lease->soft_lifetime_end_time = 0;
+
 	if (lease->state == FTS_ACTIVE) {
-		isc_heap_decreased(pool->active_timeouts, lease->heap_index);
+		if (old_end_time <= lease->hard_lifetime_end_time) {
+			isc_heap_decreased(pool->active_timeouts,
+					   lease->heap_index);
+		} else {
+			isc_heap_increased(pool->active_timeouts,
+					   lease->heap_index);
+		}
 		return ISC_R_SUCCESS;
 	} else if (lease->state == FTS_ABANDONED) {
 		char tmp_addr[INET6_ADDRSTRLEN];
@@ -1920,9 +1943,8 @@
 /*
  * Renew all leases in an IA from all pools.
  *
- * The new hard_lifetime_end_time should be updated for the addresses/prefixes.
- *
- * WARNING: lease times must only be extended, never reduced!!!
+ * The new lifetime should be in the soft_lifetime_end_time
+ * and will be moved to hard_lifetime_end_time by renew_lease6.
  */
 isc_result_t 
 renew_leases(struct ia_xx *ia) {
