diff --git a/examples/rpl_udp/main.c b/examples/rpl_udp/main.c
index f5cbe0cecd..4c88c9938b 100644
--- a/examples/rpl_udp/main.c
+++ b/examples/rpl_udp/main.c
@@ -29,7 +29,7 @@
 
 #include "rpl_udp.h"
 
-const shell_command_t shell_commands[] = {
+static const shell_command_t shell_commands[] = {
     {"init", "Initialize network", rpl_udp_init},
     {"set", "Set ID", rpl_udp_set_id},
     {"dodag", "Shows the dodag", rpl_udp_dodag},
diff --git a/examples/rpl_udp/rpl.c b/examples/rpl_udp/rpl.c
index 0b1fe6b2f6..3d4cad5dc3 100644
--- a/examples/rpl_udp/rpl.c
+++ b/examples/rpl_udp/rpl.c
@@ -35,10 +35,10 @@
 
 #define TRANSCEIVER TRANSCEIVER_DEFAULT
 
-char monitor_stack_buffer[MONITOR_STACK_SIZE];
+static char monitor_stack_buffer[MONITOR_STACK_SIZE];
 radio_address_t id;
 
-uint8_t is_root = 0;
+static uint8_t is_root = 0;
 
 void rpl_udp_init(int argc, char **argv)
 {
diff --git a/examples/rpl_udp/udp.c b/examples/rpl_udp/udp.c
index a7671ab9e9..890a181d54 100644
--- a/examples/rpl_udp/udp.c
+++ b/examples/rpl_udp/udp.c
@@ -35,7 +35,7 @@
 #define UDP_BUFFER_SIZE     (128)
 #define SERVER_PORT     (0xFF01)
 
-char udp_server_stack_buffer[KERNEL_CONF_STACKSIZE_MAIN];
+static char udp_server_stack_buffer[KERNEL_CONF_STACKSIZE_MAIN];
 char addr_str[IPV6_MAX_ADDR_STR_LEN];
 
 static void *init_udp_server(void *);