diff --git a/core/net/mac/contikimac.c b/core/net/mac/contikimac.c
index 6072e49fc..7027c5685 100644
--- a/core/net/mac/contikimac.c
+++ b/core/net/mac/contikimac.c
@@ -304,7 +304,7 @@ schedule_powercycle(struct rtimer *t, rtimer_clock_t time)
     r = rtimer_set(t, RTIMER_TIME(t) + time, 1,
                    (void (*)(struct rtimer *, void *))powercycle, NULL);
     if(r != RTIMER_OK) {
-      printf("schedule_powercycle: could not set rtimer\n");
+      PRINTF("schedule_powercycle: could not set rtimer\n");
     }
   }
 }
@@ -323,7 +323,7 @@ schedule_powercycle_fixed(struct rtimer *t, rtimer_clock_t fixed_time)
     r = rtimer_set(t, fixed_time, 1,
                    (void (*)(struct rtimer *, void *))powercycle, NULL);
     if(r != RTIMER_OK) {
-      printf("schedule_powercycle: could not set rtimer\n");
+      PRINTF("schedule_powercycle: could not set rtimer\n");
     }
   }
 }
diff --git a/core/net/rime/collect.c b/core/net/rime/collect.c
index 0c743f388..6f16b4b4d 100644
--- a/core/net/rime/collect.c
+++ b/core/net/rime/collect.c
@@ -310,7 +310,7 @@ update_parent(struct collect_conn *tc)
       bump_advertisement(tc);
     } else {
       if(DRAW_TREE) {
-        printf("#A e=%d\n", collect_neighbor_link_estimate(best));
+        PRINTF("#A e=%d\n", collect_neighbor_link_estimate(best));
       }
       if(collect_neighbor_rtmetric_link_estimate(best) +
          SIGNIFICANT_RTMETRIC_PARENT_CHANGE <
@@ -329,30 +329,30 @@ update_parent(struct collect_conn *tc)
         bump_advertisement(tc);
 
         if(DRAW_TREE) {
-          printf("#A e=%d\n", collect_neighbor_link_estimate(best));
+          PRINTF("#A e=%d\n", collect_neighbor_link_estimate(best));
           /*          {
             int i;
             int etx = 0;
-            printf("#A l=");
+            PRINTF("#A l=");
             for(i = 0; i < 8; i++) {
-              printf("%d ", best->le.history[(best->le.historyptr - 1 - i) & 7]);
+              PRINTF("%d ", best->le.history[(best->le.historyptr - 1 - i) & 7]);
               etx += current->le.history[i];
             }
-            printf("\n");
+            PRINTF("\n");
             }*/
         }
       } else {
         if(DRAW_TREE) {
-          printf("#A e=%d\n", collect_neighbor_link_estimate(current));
+          PRINTF("#A e=%d\n", collect_neighbor_link_estimate(current));
           /*          {
             int i;
             int etx = 0;
-            printf("#A l=");
+            PRINTF("#A l=");
             for(i = 0; i < 8; i++) {
-              printf("%d ", current->le.history[(current->le.historyptr - 1 - i) & 7]);
+              PRINTF("%d ", current->le.history[(current->le.historyptr - 1 - i) & 7]);
               etx += current->le.history[i];
             }
-            printf("\n");
+            PRINTF("\n");
             }*/
         }
       }
@@ -360,16 +360,16 @@ update_parent(struct collect_conn *tc)
     if(DRAW_TREE) {
       if(!rimeaddr_cmp(&previous_parent, &tc->parent)) {
         if(!rimeaddr_cmp(&previous_parent, &rimeaddr_null)) {
-          printf("#L %d 0\n", previous_parent.u8[0]);
+          PRINTF("#L %d 0\n", previous_parent.u8[0]);
         }
-        printf("#L %d 1\n", tc->parent.u8[0]);
+        PRINTF("#L %d 1\n", tc->parent.u8[0]);
       }
     }
   } else {
     /* No parent. */
     if(!rimeaddr_cmp(&tc->parent, &rimeaddr_null)) {
       if(DRAW_TREE) {
-        printf("#L %d 0\n", tc->parent.u8[0]);
+        PRINTF("#L %d 0\n", tc->parent.u8[0]);
       }
       stats.routelost++;
     }
@@ -437,7 +437,7 @@ update_rtmetric(struct collect_conn *tc)
     }
     if(DRAW_TREE) {
       if(old_rtmetric != new_rtmetric) {
-        printf("#A rt=%d,p=%d\n", tc->rtmetric, tc->parent.u8[0]);
+        PRINTF("#A rt=%d,p=%d\n", tc->rtmetric, tc->parent.u8[0]);
       }
     }
   }
@@ -772,7 +772,7 @@ handle_ack(struct collect_conn *tc)
                   &tc->current_parent) &&
      packetbuf_attr(PACKETBUF_ATTR_PACKET_ID) == tc->seqno) {
 
-    /*    printf("rtt %d / %d = %d.%02d\n",
+    /*    PRINTF("rtt %d / %d = %d.%02d\n",
            (int)(clock_time() - tc->send_time),
            (int)CLOCK_SECOND,
            (int)((clock_time() - tc->send_time) / CLOCK_SECOND),
@@ -945,7 +945,7 @@ node_packet_received(struct unicast_conn *c, const rimeaddr_t *from)
     /* If the queue is more than half filled, we add the CONGESTED
        flag to our outgoing acks. */
     if(DRAW_TREE) {
-      printf("#A s=%d\n", packetqueue_len(&tc->send_queue));
+      PRINTF("#A s=%d\n", packetqueue_len(&tc->send_queue));
     }
     if(packetqueue_len(&tc->send_queue) >= MAX_SENDING_QUEUE / 2) {
       ackflags |= ACK_FLAGS_CONGESTED;
@@ -1089,7 +1089,7 @@ timedout(struct collect_conn *tc)
 	 rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1], tc->transmissions,
          tc->current_parent.u8[0], tc->current_parent.u8[1],
          tc->max_rexmits);
-  printf("%d.%d: timedout after %d retransmissions to %d.%d (max retransmissions %d): packet dropped\n",
+  PRINTF("%d.%d: timedout after %d retransmissions to %d.%d (max retransmissions %d): packet dropped\n",
 	 rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1], tc->transmissions,
          tc->current_parent.u8[0], tc->current_parent.u8[1],
          tc->max_rexmits);
@@ -1394,7 +1394,7 @@ collect_set_sink(struct collect_conn *tc, int should_be_sink)
   bump_advertisement(tc);
 
   if(DRAW_TREE) {
-    printf("#A rt=0,p=0\n");
+    PRINTF("#A rt=0,p=0\n");
   }
 }
 /*---------------------------------------------------------------------------*/
@@ -1455,7 +1455,7 @@ collect_send(struct collect_conn *tc, int rexmits)
     } else {
       PRINTF("%d.%d: drop originated packet: no queuebuf\n",
              rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1]);
-      printf("%d.%d: drop originated packet: no queuebuf\n",
+      PRINTF("%d.%d: drop originated packet: no queuebuf\n",
              rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1]);
       ret = 0;
     }
@@ -1491,7 +1491,7 @@ collect_send(struct collect_conn *tc, int rexmits)
       } else {
         PRINTF("%d.%d: drop originated packet: no queuebuf\n",
                rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1]);
-        printf("%d.%d: drop originated packet: no queuebuf\n",
+        PRINTF("%d.%d: drop originated packet: no queuebuf\n",
                rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1]);
                }*/
     }
@@ -1518,7 +1518,7 @@ collect_purge(struct collect_conn *tc)
   rimeaddr_copy(&tc->parent, &rimeaddr_null);
   update_rtmetric(tc);
   if(DRAW_TREE) {
-    printf("#L %d 0\n", tc->parent.u8[0]);
+    PRINTF("#L %d 0\n", tc->parent.u8[0]);
   }
   rimeaddr_copy(&tc->parent, &rimeaddr_null);
 }