diff --git a/core/net/mac/csma.c b/core/net/mac/csma.c
index cb0430341..37d8f4998 100644
--- a/core/net/mac/csma.c
+++ b/core/net/mac/csma.c
@@ -186,15 +186,19 @@ free_first_packet(struct neighbor_queue *n)
 static void
 packet_sent(void *ptr, int status, int num_transmissions)
 {
-  struct neighbor_queue *n = ptr;
-  struct rdc_buf_list *q = list_head(n->queued_packet_list);
-  struct qbuf_metadata *metadata = (struct qbuf_metadata *)q->ptr;
+  struct neighbor_queue *n;
+  struct rdc_buf_list *q;
+  struct qbuf_metadata *metadata;
   clock_time_t time = 0;
   mac_callback_t sent;
   void *cptr;
   int num_tx;
   int backoff_transmissions;
 
+  n = ptr;
+  if(n == NULL) {
+    return;
+  }
   switch(status) {
   case MAC_TX_OK:
   case MAC_TX_NOACK:
@@ -208,66 +212,72 @@ packet_sent(void *ptr, int status, int num_transmissions)
     break;
   }
 
-  sent = metadata->sent;
-  cptr = metadata->cptr;
-  num_tx = n->transmissions;
+  q = list_head(n->queued_packet_list);
+  if(q != NULL) {
+    metadata = (struct qbuf_metadata *)q->ptr;
 
-  if(status == MAC_TX_COLLISION ||
-     status == MAC_TX_NOACK) {
+    if(metadata != NULL) {
+      sent = metadata->sent;
+      cptr = metadata->cptr;
+      num_tx = n->transmissions;
+      if(status == MAC_TX_COLLISION ||
+         status == MAC_TX_NOACK) {
 
-    /* If the transmission was not performed because of a collision or
-       noack, we must retransmit the packet. */
-    
-    switch(status) {
-    case MAC_TX_COLLISION:
-      PRINTF("csma: rexmit collision %d\n", n->transmissions);
-      break;
-    case MAC_TX_NOACK:
-      PRINTF("csma: rexmit noack %d\n", n->transmissions);
-      break;
-    default:
-      PRINTF("csma: rexmit err %d, %d\n", status, n->transmissions);
+        /* If the transmission was not performed because of a
+           collision or noack, we must retransmit the packet. */
+
+        switch(status) {
+        case MAC_TX_COLLISION:
+          PRINTF("csma: rexmit collision %d\n", n->transmissions);
+          break;
+        case MAC_TX_NOACK:
+          PRINTF("csma: rexmit noack %d\n", n->transmissions);
+          break;
+        default:
+          PRINTF("csma: rexmit err %d, %d\n", status, n->transmissions);
+        }
+
+        /* The retransmission time must be proportional to the channel
+           check interval of the underlying radio duty cycling layer. */
+        time = default_timebase();
+
+        /* The retransmission time uses a linear backoff so that the
+           interval between the transmissions increase with each
+           retransmit. */
+        backoff_transmissions = n->transmissions + 1;
+        
+        /* Clamp the number of backoffs so that we don't get a too long
+           timeout here, since that will delay all packets in the
+           queue. */
+        if(backoff_transmissions > 3) {
+          backoff_transmissions = 3;
+        }
+        
+        time = time + (random_rand() % (backoff_transmissions * time));
+        
+        if(n->transmissions < metadata->max_transmissions) {
+          PRINTF("csma: retransmitting with time %lu %p\n", time, q);
+          ctimer_set(&n->transmit_timer, time,
+                     transmit_packet_list, n);
+          /* This is needed to correctly attribute energy that we spent
+             transmitting this packet. */
+          queuebuf_update_attr_from_packetbuf(q->buf);
+        } else {
+          PRINTF("csma: drop with status %d after %d transmissions, %d collisions\n",
+                 status, n->transmissions, n->collisions);
+          free_first_packet(n);
+          mac_call_sent_callback(sent, cptr, status, num_tx);
+        }
+      } else {
+        if(status == MAC_TX_OK) {
+          PRINTF("csma: rexmit ok %d\n", n->transmissions);
+        } else {
+          PRINTF("csma: rexmit failed %d: %d\n", n->transmissions, status);
+        }
+        free_first_packet(n);
+        mac_call_sent_callback(sent, cptr, status, num_tx);
+      }
     }
-
-    /* The retransmission time must be proportional to the channel
-       check interval of the underlying radio duty cycling layer. */
-    time = default_timebase();
-
-    /* The retransmission time uses a linear backoff so that the
-       interval between the transmissions increase with each
-       retransmit. */
-    backoff_transmissions = n->transmissions + 1;
-
-    /* Clamp the number of backoffs so that we don't get a too long
-       timeout here, since that will delay all packets in the
-       queue. */
-    if(backoff_transmissions > 3) {
-      backoff_transmissions = 3;
-    }
-
-    time = time + (random_rand() % (backoff_transmissions * time));
-
-    if(n->transmissions < metadata->max_transmissions) {
-      PRINTF("csma: retransmitting with time %lu %p\n", time, q);
-      ctimer_set(&n->transmit_timer, time,
-                 transmit_packet_list, n);
-      /* This is needed to correctly attribute energy that we spent
-         transmitting this packet. */
-      queuebuf_update_attr_from_packetbuf(q->buf);
-    } else {
-      PRINTF("csma: drop with status %d after %d transmissions, %d collisions\n",
-             status, n->transmissions, n->collisions);
-      free_first_packet(n);
-      mac_call_sent_callback(sent, cptr, status, num_tx);
-    }
-  } else {
-    if(status == MAC_TX_OK) {
-      PRINTF("csma: rexmit ok %d\n", n->transmissions);
-    } else {
-      PRINTF("csma: rexmit failed %d: %d\n", n->transmissions, status);
-    }
-    free_first_packet(n);
-    mac_call_sent_callback(sent, cptr, status, num_tx);
   }
 }
 /*---------------------------------------------------------------------------*/
@@ -277,86 +287,77 @@ send_packet(mac_callback_t sent, void *ptr)
   struct rdc_buf_list *q;
   struct neighbor_queue *n;
   static uint16_t seqno;
+  const rimeaddr_t *addr = packetbuf_addr(PACKETBUF_ADDR_RECEIVER);
 
   packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, seqno++);
-  
-  /* If the packet is a broadcast, do not allocate a queue
-     entry. Instead, just send it out.  */
-  if(!rimeaddr_cmp(packetbuf_addr(PACKETBUF_ADDR_RECEIVER),
-                   &rimeaddr_null)) {
-    const rimeaddr_t *addr = packetbuf_addr(PACKETBUF_ADDR_RECEIVER);
-
-    /* Look for the neighbor entry */
-    n = neighbor_queue_from_addr(addr);
-    if(n == NULL) {
-      /* Allocate a new neighbor entry */
-      n = memb_alloc(&neighbor_memb);
-      if(n != NULL) {
-        /* Init neighbor entry */
-        rimeaddr_copy(&n->addr, addr);
-        n->transmissions = 0;
-        n->collisions = 0;
-        n->deferrals = 0;
-        /* Init packet list for this neighbor */
-        LIST_STRUCT_INIT(n, queued_packet_list);
-        /* Add neighbor to the list */
-        list_add(neighbor_list, n);
-      }
-    }
 
+  /* Look for the neighbor entry */
+  n = neighbor_queue_from_addr(addr);
+  if(n == NULL) {
+    /* Allocate a new neighbor entry */
+    n = memb_alloc(&neighbor_memb);
     if(n != NULL) {
-      /* Add packet to the neighbor's queue */
-      q = memb_alloc(&packet_memb);
-      if(q != NULL) {
-        q->ptr = memb_alloc(&metadata_memb);
-        if(q->ptr != NULL) {
-          q->buf = queuebuf_new_from_packetbuf();
-          if(q->buf != NULL) {
-            struct qbuf_metadata *metadata = (struct qbuf_metadata *)q->ptr;
-            /* Neighbor and packet successfully allocated */
-            if(packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS) == 0) {
-              /* Use default configuration for max transmissions */
-              metadata->max_transmissions = CSMA_MAX_MAC_TRANSMISSIONS;
-            } else {
-              metadata->max_transmissions =
-                  packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
-            }
-            metadata->sent = sent;
-            metadata->cptr = ptr;
-
-            if(packetbuf_attr(PACKETBUF_ATTR_PACKET_TYPE) ==
-                PACKETBUF_ATTR_PACKET_TYPE_ACK) {
-              list_push(n->queued_packet_list, q);
-            } else {
-              list_add(n->queued_packet_list, q);
-            }
-
-            /* If q is the first packet in the neighbor's queue, send asap */
-            if(list_head(n->queued_packet_list) == q) {
-              ctimer_set(&n->transmit_timer, 0, transmit_packet_list, n);
-            }
-            return;
-          }
-          memb_free(&metadata_memb, q->ptr);
-          PRINTF("csma: could not allocate queuebuf, dropping packet\n");
-        }
-        memb_free(&packet_memb, q);
-        PRINTF("csma: could not allocate queuebuf, dropping packet\n");
-      }
-      /* The packet allocation failed. Remove and free neighbor entry if empty. */
-      if(list_length(n->queued_packet_list) == 0) {
-        list_remove(neighbor_list, n);
-        memb_free(&neighbor_memb, n);
-      }
-      PRINTF("csma: could not allocate packet, dropping packet\n");
-    } else {
-      PRINTF("csma: could not allocate neighbor, dropping packet\n");
+      /* Init neighbor entry */
+      rimeaddr_copy(&n->addr, addr);
+      n->transmissions = 0;
+      n->collisions = 0;
+      n->deferrals = 0;
+      /* Init packet list for this neighbor */
+      LIST_STRUCT_INIT(n, queued_packet_list);
+      /* Add neighbor to the list */
+      list_add(neighbor_list, n);
     }
-    mac_call_sent_callback(sent, ptr, MAC_TX_ERR, 1);
-  } else {
-    PRINTF("csma: send broadcast\n");
-    NETSTACK_RDC.send(sent, ptr);
   }
+
+  if(n != NULL) {
+    /* Add packet to the neighbor's queue */
+    q = memb_alloc(&packet_memb);
+    if(q != NULL) {
+      q->ptr = memb_alloc(&metadata_memb);
+      if(q->ptr != NULL) {
+	q->buf = queuebuf_new_from_packetbuf();
+	if(q->buf != NULL) {
+	  struct qbuf_metadata *metadata = (struct qbuf_metadata *)q->ptr;
+	  /* Neighbor and packet successfully allocated */
+	  if(packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS) == 0) {
+	    /* Use default configuration for max transmissions */
+	    metadata->max_transmissions = CSMA_MAX_MAC_TRANSMISSIONS;
+	  } else {
+	    metadata->max_transmissions =
+                  packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
+	  }
+	  metadata->sent = sent;
+	  metadata->cptr = ptr;
+
+	  if(packetbuf_attr(PACKETBUF_ATTR_PACKET_TYPE) ==
+	     PACKETBUF_ATTR_PACKET_TYPE_ACK) {
+	    list_push(n->queued_packet_list, q);
+	  } else {
+	    list_add(n->queued_packet_list, q);
+	  }
+
+	  /* If q is the first packet in the neighbor's queue, send asap */
+	  if(list_head(n->queued_packet_list) == q) {
+	    ctimer_set(&n->transmit_timer, 0, transmit_packet_list, n);
+	  }
+	  return;
+	}
+	memb_free(&metadata_memb, q->ptr);
+	PRINTF("csma: could not allocate queuebuf, dropping packet\n");
+      }
+      memb_free(&packet_memb, q);
+      PRINTF("csma: could not allocate queuebuf, dropping packet\n");
+    }
+    /* The packet allocation failed. Remove and free neighbor entry if empty. */
+    if(list_length(n->queued_packet_list) == 0) {
+      list_remove(neighbor_list, n);
+      memb_free(&neighbor_memb, n);
+    }
+    PRINTF("csma: could not allocate packet, dropping packet\n");
+  } else {
+    PRINTF("csma: could not allocate neighbor, dropping packet\n");
+  }
+  mac_call_sent_callback(sent, ptr, MAC_TX_ERR, 1);
 }
 /*---------------------------------------------------------------------------*/
 static void