diff --git a/core/net/mac/contikimac.c b/core/net/mac/contikimac.c
index 628be7ee4..ff4809bc0 100644
--- a/core/net/mac/contikimac.c
+++ b/core/net/mac/contikimac.c
@@ -548,7 +548,7 @@ send_packet(mac_callback_t mac_callback, void *mac_callback_ptr, struct rdc_buf_
 #if WITH_PHASE_OPTIMIZATION
     ret = phase_wait(&phase_list, packetbuf_addr(PACKETBUF_ADDR_RECEIVER),
                      CYCLE_TIME, GUARD_TIME,
-                     mac_callback, mac_callback_ptr, buf_list, 0);
+                     mac_callback, mac_callback_ptr, buf_list);
     if(ret == PHASE_DEFERRED) {
       return MAC_TX_DEFERRED;
     }
@@ -748,14 +748,8 @@ qsend_list(mac_callback_t sent, void *ptr, struct rdc_buf_list *buf_list)
   }
   /* Do not send during reception of a burst */
   if(we_are_receiving_burst) {
-    queuebuf_to_packetbuf(curr->buf);
-    /* We try to defer, and return an error this wasn't possible */
-    int ret = phase_wait(&phase_list, packetbuf_addr(PACKETBUF_ADDR_RECEIVER),
-        CYCLE_TIME, GUARD_TIME,
-        sent, ptr, curr, 2);
-    if(ret != PHASE_DEFERRED) {
-      mac_call_sent_callback(sent, ptr, MAC_TX_ERR, 1);
-    }
+    /* Return COLLISION so the MAC may try again later */
+    mac_call_sent_callback(sent, ptr, MAC_TX_COLLISION, 1);
     return;
   }
   /* The receiver needs to be awoken before we send */
diff --git a/core/net/mac/phase.c b/core/net/mac/phase.c
index 513330181..6e29ed959 100644
--- a/core/net/mac/phase.c
+++ b/core/net/mac/phase.c
@@ -167,7 +167,7 @@ phase_wait(struct phase_list *list,
            const rimeaddr_t *neighbor, rtimer_clock_t cycle_time,
            rtimer_clock_t guard_time,
            mac_callback_t mac_callback, void *mac_callback_ptr,
-           struct rdc_buf_list *buf_list, int extra_deferment)
+           struct rdc_buf_list *buf_list)
 {
   struct phase *e;
   //  const rimeaddr_t *neighbor = packetbuf_addr(PACKETBUF_ADDR_RECEIVER);
@@ -176,7 +176,7 @@ phase_wait(struct phase_list *list,
      time for the next expected phase and setup a ctimer to switch on
      the radio just before the phase. */
   e = find_neighbor(list, neighbor);
-  if((e != NULL) | extra_deferment) {
+  if(e != NULL) {
     rtimer_clock_t wait, now, expected, sync;
     clock_time_t ctimewait;
     
@@ -202,14 +202,10 @@ phase_wait(struct phase_list *list,
     if(wait < guard_time) {
       wait += cycle_time;
     }
-    if(extra_deferment) {
-      wait += extra_deferment * cycle_time;
-    }
-
 
     ctimewait = (CLOCK_SECOND * (wait - guard_time)) / RTIMER_ARCH_SECOND;
 
-    if((ctimewait > PHASE_DEFER_THRESHOLD) | extra_deferment) {
+    if(ctimewait > PHASE_DEFER_THRESHOLD) {
       struct phase_queueitem *p;
       
       p = memb_alloc(&queued_packets_memb);
diff --git a/core/net/mac/phase.h b/core/net/mac/phase.h
index 1ce17a697..d74431fcc 100644
--- a/core/net/mac/phase.h
+++ b/core/net/mac/phase.h
@@ -76,7 +76,7 @@ void phase_init(struct phase_list *list);
 phase_status_t phase_wait(struct phase_list *list,  const rimeaddr_t *neighbor,
                           rtimer_clock_t cycle_time, rtimer_clock_t wait_before,
                           mac_callback_t mac_callback, void *mac_callback_ptr,
-                          struct rdc_buf_list *buf_list, int extra_deferment);
+                          struct rdc_buf_list *buf_list);
 void phase_update(const struct phase_list *list, const rimeaddr_t *neighbor,
                   rtimer_clock_t time, int mac_status);