diff --git a/os/net/mac/csma/csma-output.c b/os/net/mac/csma/csma-output.c
index ebea0fd8a..653743967 100644
--- a/os/net/mac/csma/csma-output.c
+++ b/os/net/mac/csma/csma-output.c
@@ -50,6 +50,7 @@
 #include "net/netstack.h"
 #include "lib/list.h"
 #include "lib/memb.h"
+#include "lib/assert.h"
 
 /* Log configuration */
 #include "sys/log.h"
@@ -131,7 +132,10 @@ MEMB(packet_memb, struct packet_queue, MAX_QUEUED_PACKETS);
 MEMB(metadata_memb, struct qbuf_metadata, MAX_QUEUED_PACKETS);
 LIST(neighbor_list);
 
-static void packet_sent(void *ptr, int status, int num_transmissions);
+static void packet_sent(struct neighbor_queue *n,
+    struct packet_queue *q,
+    int status,
+    int num_transmissions);
 static void transmit_from_queue(void *ptr);
 /*---------------------------------------------------------------------------*/
 static struct neighbor_queue *
@@ -162,7 +166,7 @@ backoff_period(void)
 }
 /*---------------------------------------------------------------------------*/
 static int
-send_one_packet(void *ptr)
+send_one_packet(struct neighbor_queue *n, struct packet_queue *q)
 {
   int ret;
   int last_sent_ok = 0;
@@ -245,7 +249,7 @@ send_one_packet(void *ptr)
     last_sent_ok = 1;
   }
 
-  packet_sent(ptr, ret, 1);
+  packet_sent(n, q, ret, 1);
   return last_sent_ok;
 }
 /*---------------------------------------------------------------------------*/
@@ -263,7 +267,7 @@ transmit_from_queue(void *ptr)
         n->transmissions, list_length(n->packet_queue));
       /* Send first packet in the neighbor queue */
       queuebuf_to_packetbuf(q->buf);
-      send_one_packet(n);
+      send_one_packet(n, q);
     }
   }
 }
@@ -396,30 +400,15 @@ tx_ok(struct packet_queue *q, struct neighbor_queue *n, int num_transmissions)
 }
 /*---------------------------------------------------------------------------*/
 static void
-packet_sent(void *ptr, int status, int num_transmissions)
+packet_sent(struct neighbor_queue *n,
+    struct packet_queue *q,
+    int status,
+    int num_transmissions)
 {
-  struct neighbor_queue *n;
-  struct packet_queue *q;
+  assert(n != NULL);
+  assert(q != NULL);
 
-  n = ptr;
-  if(n == NULL) {
-    return;
-  }
-
-  /* Find out what packet this callback refers to */
-  for(q = list_head(n->packet_queue);
-      q != NULL; q = list_item_next(q)) {
-    if(queuebuf_attr(q->buf, PACKETBUF_ATTR_MAC_SEQNO) ==
-       packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO)) {
-      break;
-    }
-  }
-
-  if(q == NULL) {
-    LOG_WARN("packet sent: seqno %u not found\n",
-           packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO));
-    return;
-  } else if(q->ptr == NULL) {
+  if(q->ptr == NULL) {
     LOG_WARN("packet sent: no metadata\n");
     return;
   }
diff --git a/os/net/mac/csma/csma.c b/os/net/mac/csma/csma.c
index 63808192f..87aa6a1af 100644
--- a/os/net/mac/csma/csma.c
+++ b/os/net/mac/csma/csma.c
@@ -75,11 +75,7 @@ static void
 input_packet(void)
 {
 #if CSMA_SEND_SOFT_ACK
-  int original_datalen;
-  uint8_t *original_dataptr;
-
-  original_datalen = packetbuf_datalen();
-  original_dataptr = packetbuf_dataptr();
+  uint8_t ackdata[CSMA_ACK_LEN];
 #endif
 
   if(packetbuf_datalen() == CSMA_ACK_LEN) {
@@ -91,6 +87,8 @@ input_packet(void)
                                          &linkaddr_node_addr) &&
             !packetbuf_holds_broadcast()) {
     LOG_WARN("not for us\n");
+  } else if(linkaddr_cmp(packetbuf_addr(PACKETBUF_ADDR_SENDER), &linkaddr_node_addr)) {
+    LOG_WARN("frame from ourselves\n");
   } else {
     int duplicate = 0;
 
@@ -106,20 +104,11 @@ input_packet(void)
     }
 
 #if CSMA_SEND_SOFT_ACK
-    {
-      frame802154_t info154;
-      frame802154_parse(original_dataptr, original_datalen, &info154);
-      if(info154.fcf.frame_type == FRAME802154_DATAFRAME &&
-         info154.fcf.ack_required != 0 &&
-         linkaddr_cmp((linkaddr_t *)&info154.dest_addr,
-                      &linkaddr_node_addr)) {
-        uint8_t ackdata[CSMA_ACK_LEN] = {0, 0, 0};
-
-        ackdata[0] = FRAME802154_ACKFRAME;
-        ackdata[1] = 0;
-        ackdata[2] = info154.seq;
-        NETSTACK_RADIO.send(ackdata, CSMA_ACK_LEN);
-      }
+    if(packetbuf_attr(PACKETBUF_ATTR_MAC_ACK)) {
+      ackdata[0] = FRAME802154_ACKFRAME;
+      ackdata[1] = 0;
+      ackdata[2] = ((uint8_t *)packetbuf_hdrptr())[2];
+      NETSTACK_RADIO.send(ackdata, CSMA_ACK_LEN);
     }
 #endif /* CSMA_SEND_SOFT_ACK */
     if(!duplicate) {
diff --git a/os/net/mac/framer/framer-802154.c b/os/net/mac/framer/framer-802154.c
index b4c24da19..8e92b9b2d 100644
--- a/os/net/mac/framer/framer-802154.c
+++ b/os/net/mac/framer/framer-802154.c
@@ -240,6 +240,7 @@ parse(void)
 
   if(hdr_len && packetbuf_hdrreduce(hdr_len)) {
     packetbuf_set_attr(PACKETBUF_ATTR_FRAME_TYPE, frame.fcf.frame_type);
+    packetbuf_set_attr(PACKETBUF_ATTR_MAC_ACK, frame.fcf.ack_required);
 
     if(frame.fcf.dest_addr_mode) {
       if(frame.dest_pid != frame802154_get_pan_id() &&
diff --git a/os/net/mac/framer/nullframer.c b/os/net/mac/framer/nullframer.c
index 019ed2209..ae7bc925d 100644
--- a/os/net/mac/framer/nullframer.c
+++ b/os/net/mac/framer/nullframer.c
@@ -87,6 +87,7 @@ parse(void)
     }
     packetbuf_set_addr(PACKETBUF_ADDR_SENDER, (linkaddr_t *)&frame.src_addr);
     packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, frame.seq);
+    packetbuf_set_attr(PACKETBUF_ATTR_MAC_ACK, frame.fcf.ack_required);
     return 0;
   }
 #endif