diff --git a/examples/nullnet/nullnet-broadcast.c b/examples/nullnet/nullnet-broadcast.c
index f40b62871..d654784eb 100644
--- a/examples/nullnet/nullnet-broadcast.c
+++ b/examples/nullnet/nullnet-broadcast.c
@@ -57,11 +57,6 @@
 static linkaddr_t coordinator_addr =  {{ 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }};
 #endif /* MAC_CONF_WITH_TSCH */
 
-static uint32_t buffer[128];
-uint8_t *nullnet_buf = (uint8_t *)buffer; 
-uint16_t nullnet_len;
-
-
 /*---------------------------------------------------------------------------*/
 PROCESS(nullnet_example_process, "NullNet broadcast example");
 AUTOSTART_PROCESSES(&nullnet_example_process);
@@ -86,6 +81,9 @@ PROCESS_THREAD(nullnet_example_process, ev, data)
   tsch_set_coordinator(linkaddr_cmp(&coordinator_addr, &linkaddr_node_addr));
 #endif /* MAC_CONF_WITH_TSCH */
 
+  /* Initialize NullNet */
+  nullnet_buf = (uint8_t *)&count;
+  nullnet_len = sizeof(count);
   nullnet_set_input_callback(input_callback);
 
   etimer_set(&periodic_timer, SEND_INTERVAL);
diff --git a/examples/nullnet/nullnet-unicast.c b/examples/nullnet/nullnet-unicast.c
index 3518caea3..98866f381 100644
--- a/examples/nullnet/nullnet-unicast.c
+++ b/examples/nullnet/nullnet-unicast.c
@@ -59,10 +59,6 @@ static linkaddr_t dest_addr =         {{ 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0
 static linkaddr_t coordinator_addr =  {{ 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }};
 #endif /* MAC_CONF_WITH_TSCH */
 
-static uint32_t buffer[128];
-uint8_t *nullnet_buf = (uint8_t *)buffer; 
-uint16_t nullnet_len;
-
 /*---------------------------------------------------------------------------*/
 PROCESS(nullnet_example_process, "NullNet unicast example");
 AUTOSTART_PROCESSES(&nullnet_example_process);
@@ -87,6 +83,9 @@ PROCESS_THREAD(nullnet_example_process, ev, data)
   tsch_set_coordinator(linkaddr_cmp(&coordinator_addr, &linkaddr_node_addr));
 #endif /* MAC_CONF_WITH_TSCH */
 
+  /* Initialize NullNet */
+  nullnet_buf = (uint8_t *)&count;
+  nullnet_len = sizeof(count);
   nullnet_set_input_callback(input_callback);
 
   if(!linkaddr_cmp(&dest_addr, &linkaddr_node_addr)) {
@@ -97,9 +96,6 @@ PROCESS_THREAD(nullnet_example_process, ev, data)
       LOG_INFO_LLADDR(&dest_addr);
       LOG_INFO_("\n");
 
-      memcpy(nullnet_buf, &count, sizeof(count));
-      nullnet_len = sizeof(count);
-
       NETSTACK_NETWORK.output(&dest_addr);
       count++;
       etimer_reset(&periodic_timer);
diff --git a/os/net/nullnet/nullnet.c b/os/net/nullnet/nullnet.c
index 0841379ec..298b2e9cd 100644
--- a/os/net/nullnet/nullnet.c
+++ b/os/net/nullnet/nullnet.c
@@ -53,6 +53,8 @@
 #define LOG_MODULE "NullNet"
 #define LOG_LEVEL LOG_LEVEL_NULLNET
 
+uint8_t *nullnet_buf;
+uint16_t nullnet_len;
 static nullnet_input_callback current_callback = NULL;
 /*--------------------------------------------------------------------*/
 static void
diff --git a/os/net/nullnet/nullnet.h b/os/net/nullnet/nullnet.h
index c719b0c80..35b58effe 100644
--- a/os/net/nullnet/nullnet.h
+++ b/os/net/nullnet/nullnet.h
@@ -52,6 +52,9 @@ for non-IPv6 scenarios.
 #include "contiki.h"
 #include "net/linkaddr.h"
 
+/**
+ * Buffer used by the output function
+*/
 extern uint8_t *nullnet_buf;
 extern uint16_t nullnet_len;