diff --git a/core/net/mac/contikimac.c b/core/net/mac/contikimac.c
index ff939560f..8ac826867 100644
--- a/core/net/mac/contikimac.c
+++ b/core/net/mac/contikimac.c
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: contikimac.c,v 1.28 2010/04/04 21:01:24 adamdunkels Exp $
+ * $Id: contikimac.c,v 1.29 2010/04/05 19:28:07 adamdunkels Exp $
  */
 
 /**
@@ -192,6 +192,8 @@ static volatile rtimer_clock_t stream_until;
 #define MIN(a, b) ((a) < (b)? (a) : (b))
 #endif /* MIN */
 
+static int last_received_seqno;
+static rimeaddr_t last_received_sender;
 
 /*---------------------------------------------------------------------------*/
 static void
@@ -862,7 +864,21 @@ input_packet(void)
         phase_remove(&phase_list, packetbuf_addr(PACKETBUF_ADDR_SENDER));
       }
 #endif /* WITH_PHASE_OPTIMIZATION */
-      
+
+      /* Check for duplicate packet by comparing the sequence number
+         of the incoming packet with the last one we saw. */
+      if(packetbuf_attr(PACKETBUF_ATTR_PACKET_ID) == last_received_seqno &&
+         rimeaddr_cmp(packetbuf_addr(PACKETBUF_ADDR_SENDER),
+                      &last_received_sender)) {
+        /* Drop the packet. */
+        /*        printf("Drop duplicate ContikiMAC layer packet\n");*/
+        return;
+      }
+
+
+      last_received_seqno = packetbuf_attr(PACKETBUF_ATTR_PACKET_ID);
+      rimeaddr_copy(&last_received_sender, packetbuf_addr(PACKETBUF_ADDR_SENDER));
+
 #if CONTIKIMAC_CONF_COMPOWER
       /* Accumulate the power consumption for the packet reception. */
       compower_accumulate(&current_packet);
diff --git a/core/net/mac/framer-802154.c b/core/net/mac/framer-802154.c
index 099da18c0..72dbc347a 100644
--- a/core/net/mac/framer-802154.c
+++ b/core/net/mac/framer-802154.c
@@ -26,7 +26,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: framer-802154.c,v 1.8 2010/04/03 13:28:30 adamdunkels Exp $
+ * $Id: framer-802154.c,v 1.9 2010/04/05 19:28:07 adamdunkels Exp $
  */
 
 /**
@@ -186,7 +186,7 @@ parse(void)
     packetbuf_set_addr(PACKETBUF_ADDR_SENDER, (rimeaddr_t *)&frame.src_addr);
     packetbuf_set_attr(PACKETBUF_ATTR_PENDING, frame.fcf.frame_pending);
     /*    packetbuf_set_attr(PACKETBUF_ATTR_RELIABLE, frame.fcf.ack_required);*/
-    /*    packetbuf_set_attr(PACKETBUF_ATTR_PACKET_ID, frame.seq);*/
+    packetbuf_set_attr(PACKETBUF_ATTR_PACKET_ID, frame.seq);
 
     PRINTF("15.4-IN: %2X", frame.fcf.frame_type);
     PRINTADDR(packetbuf_addr(PACKETBUF_ADDR_SENDER));