diff --git a/examples/ipv6/rpl-collect/Makefile b/examples/ipv6/rpl-collect/Makefile
index c2e7875ef..e37b71468 100644
--- a/examples/ipv6/rpl-collect/Makefile
+++ b/examples/ipv6/rpl-collect/Makefile
@@ -7,6 +7,10 @@ WITH_UIP6=1
 UIP_CONF_IPV6=1
 CFLAGS+= -DUIP_CONF_IPV6_RPL
 
+ifdef PERIOD
+CFLAGS=-DPERIOD=$(PERIOD)
+endif
+
 all: $(CONTIKI_PROJECT)
 
 include $(CONTIKI)/Makefile.include
diff --git a/examples/ipv6/rpl-collect/collect-common.c b/examples/ipv6/rpl-collect/collect-common.c
index f0257df51..aa5bcf5d8 100644
--- a/examples/ipv6/rpl-collect/collect-common.c
+++ b/examples/ipv6/rpl-collect/collect-common.c
@@ -49,8 +49,10 @@
 static unsigned long time_offset;
 static int send_active = 1;
 
+#ifndef PERIOD
 #define PERIOD 60
-#define RANDWAIT 60
+#endif
+#define RANDWAIT (PERIOD)
 
 /*---------------------------------------------------------------------------*/
 PROCESS(collect_common_process, "collect common process");