diff --git a/regression-tests/23-rpl-non-storing/01-rpl-up-route.csc b/regression-tests/23-rpl-non-storing/01-rpl-up-route.csc
index fc79cfc27..da4743d44 100644
--- a/regression-tests/23-rpl-non-storing/01-rpl-up-route.csc
+++ b/regression-tests/23-rpl-non-storing/01-rpl-up-route.csc
@@ -323,11 +323,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/02-rpl-root-reboot.csc b/regression-tests/23-rpl-non-storing/02-rpl-root-reboot.csc
index 14f87c7a9..6c4ce9d28 100644
--- a/regression-tests/23-rpl-non-storing/02-rpl-root-reboot.csc
+++ b/regression-tests/23-rpl-non-storing/02-rpl-root-reboot.csc
@@ -323,11 +323,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/03-rpl-28-hours.csc b/regression-tests/23-rpl-non-storing/03-rpl-28-hours.csc
index 1cf2c5e43..3ebc7adda 100644
--- a/regression-tests/23-rpl-non-storing/03-rpl-28-hours.csc
+++ b/regression-tests/23-rpl-non-storing/03-rpl-28-hours.csc
@@ -272,11 +272,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/04-rpl-large-network.csc b/regression-tests/23-rpl-non-storing/04-rpl-large-network.csc
index e40b7a339..f4ea0fda8 100644
--- a/regression-tests/23-rpl-non-storing/04-rpl-large-network.csc
+++ b/regression-tests/23-rpl-non-storing/04-rpl-large-network.csc
@@ -7038,11 +7038,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/05-rpl-up-and-down-routes.csc b/regression-tests/23-rpl-non-storing/05-rpl-up-and-down-routes.csc
index c2b3cb506..0dd110738 100644
--- a/regression-tests/23-rpl-non-storing/05-rpl-up-and-down-routes.csc
+++ b/regression-tests/23-rpl-non-storing/05-rpl-up-and-down-routes.csc
@@ -321,11 +321,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/06-rpl-temporary-root-loss.csc b/regression-tests/23-rpl-non-storing/06-rpl-temporary-root-loss.csc
index 6b5c91e54..6c29c643f 100644
--- a/regression-tests/23-rpl-non-storing/06-rpl-temporary-root-loss.csc
+++ b/regression-tests/23-rpl-non-storing/06-rpl-temporary-root-loss.csc
@@ -327,11 +327,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-0.csc b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-0.csc
index b5aeac9b2..0fc6e032d 100644
--- a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-0.csc
+++ b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-0.csc
@@ -339,11 +339,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-1.csc b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-1.csc
index d17bc193c..2c0ce41ff 100644
--- a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-1.csc
+++ b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-1.csc
@@ -339,11 +339,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-2.csc b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-2.csc
index fe3db3dc3..cdb2bd748 100644
--- a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-2.csc
+++ b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-2.csc
@@ -339,11 +339,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-3.csc b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-3.csc
index 7ee838b2c..34b930c0d 100644
--- a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-3.csc
+++ b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-3.csc
@@ -339,11 +339,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-4.csc b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-4.csc
index 35c5bd753..ff9a400c1 100644
--- a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-4.csc
+++ b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-4.csc
@@ -339,11 +339,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-5.csc b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-5.csc
index 4dc5038bc..e491b666f 100644
--- a/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-5.csc
+++ b/regression-tests/23-rpl-non-storing/08-rpl-dao-route-loss-5.csc
@@ -339,11 +339,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/09-rpl-probing.csc b/regression-tests/23-rpl-non-storing/09-rpl-probing.csc
index 5206f1cfd..66a156e9c 100644
--- a/regression-tests/23-rpl-non-storing/09-rpl-probing.csc
+++ b/regression-tests/23-rpl-non-storing/09-rpl-probing.csc
@@ -234,12 +234,12 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
         lastMsgHops = hops;
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/10-rpl-multi-dodag.csc b/regression-tests/23-rpl-non-storing/10-rpl-multi-dodag.csc
index fa015e8d9..0f446cc65 100644
--- a/regression-tests/23-rpl-non-storing/10-rpl-multi-dodag.csc
+++ b/regression-tests/23-rpl-non-storing/10-rpl-multi-dodag.csc
@@ -368,11 +368,11 @@ while(true) {
             lostMsgs += numMissed;           
             log.log("Missed messages " + numMissed + " before " + num + "\n");            
             for(i = 0; i < numMissed; i++) {
-                packets = packets.substr(0, lastMsg + i + 1) + "_";    
+                packets = packets.substr(0, lastMsg + i + 1).concat("_");    
             }
           }    
         }
-        packets = packets.substr(0, num) + "*";
+        packets = packets.substr(0, num).concat("*");
         log.log("" + hops + " " + packets + "\n");
         lastMsg = num;
     }
diff --git a/regression-tests/23-rpl-non-storing/code/receiver-node.c b/regression-tests/23-rpl-non-storing/code/receiver-node.c
index 4ba3cb148..727a23f84 100644
--- a/regression-tests/23-rpl-non-storing/code/receiver-node.c
+++ b/regression-tests/23-rpl-non-storing/code/receiver-node.c
@@ -73,7 +73,7 @@ set_global_address(void)
   int i;
   uint8_t state;
 
-  uip_ip6addr(&ipaddr, 0xaaaa, 0, 0, 0, 0, 0, 0, 0);
+  uip_ip6addr(&ipaddr, UIP_DS6_DEFAULT_PREFIX, 0, 0, 0, 0, 0, 0, 0);
   uip_ds6_set_addr_iid(&ipaddr, &uip_lladdr);
   uip_ds6_addr_add(&ipaddr, 0, ADDR_AUTOCONF);
 
diff --git a/regression-tests/23-rpl-non-storing/code/root-node.c b/regression-tests/23-rpl-non-storing/code/root-node.c
index 0609e1bd8..fdea828f8 100644
--- a/regression-tests/23-rpl-non-storing/code/root-node.c
+++ b/regression-tests/23-rpl-non-storing/code/root-node.c
@@ -77,7 +77,7 @@ set_global_address(void)
   int i;
   uint8_t state;
 
-  uip_ip6addr(&ipaddr, 0xaaaa, 0, 0, 0, 0, 0, 0, 0);
+  uip_ip6addr(&ipaddr, UIP_DS6_DEFAULT_PREFIX, 0, 0, 0, 0, 0, 0, 0);
   uip_ds6_set_addr_iid(&ipaddr, &uip_lladdr);
   uip_ds6_addr_add(&ipaddr, 0, ADDR_AUTOCONF);
 
@@ -106,7 +106,7 @@ create_rpl_dag(uip_ipaddr_t *ipaddr)
     
     rpl_set_root(RPL_DEFAULT_INSTANCE, ipaddr);
     dag = rpl_get_any_dag();
-    uip_ip6addr(&prefix, 0xaaaa, 0, 0, 0, 0, 0, 0, 0);
+    uip_ip6addr(&prefix, UIP_DS6_DEFAULT_PREFIX, 0, 0, 0, 0, 0, 0, 0);
     rpl_set_prefix(dag, &prefix, 64);
     PRINTF("created a new RPL dag\n");
   } else {
diff --git a/regression-tests/23-rpl-non-storing/code/sender-node.c b/regression-tests/23-rpl-non-storing/code/sender-node.c
index 08d81b62d..55dfdd15f 100644
--- a/regression-tests/23-rpl-non-storing/code/sender-node.c
+++ b/regression-tests/23-rpl-non-storing/code/sender-node.c
@@ -72,7 +72,7 @@ set_global_address(void)
   int i;
   uint8_t state;
 
-  uip_ip6addr(&ipaddr, 0xaaaa, 0, 0, 0, 0, 0, 0, 0);
+  uip_ip6addr(&ipaddr, UIP_DS6_DEFAULT_PREFIX, 0, 0, 0, 0, 0, 0, 0);
   uip_ds6_set_addr_iid(&ipaddr, &uip_lladdr);
   uip_ds6_addr_add(&ipaddr, 0, ADDR_AUTOCONF);
 
@@ -109,7 +109,7 @@ PROCESS_THREAD(sender_node_process, ev, data)
 
     PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&send_timer));
 
-    uip_ip6addr(&addr, 0xaaaa, 0, 0, 0, 0x0201, 0x001, 0x001, 0x001);
+    uip_ip6addr(&addr, UIP_DS6_DEFAULT_PREFIX, 0, 0, 0, 0x0201, 0x001, 0x001, 0x001);
 
     {
       static unsigned int message_number;