diff --git a/dist/tools/ethos/ethos.c b/dist/tools/ethos/ethos.c
index 626ffd6e88..bef70d6955 100644
--- a/dist/tools/ethos/ethos.c
+++ b/dist/tools/ethos/ethos.c
@@ -156,7 +156,7 @@ typedef struct {
  **************************************************************************/
 int tun_alloc(char *dev, int flags) {
 
-  struct ifreq ifr;
+  struct ifreq ifr = { 0 };
   int fd, err;
 
   if( (fd = open("/dev/net/tun", O_RDWR)) < 0 ) {
@@ -164,12 +164,10 @@ int tun_alloc(char *dev, int flags) {
     return fd;
   }
 
-  memset(&ifr, 0, sizeof(ifr));
-
   ifr.ifr_flags = flags;
 
   if (*dev) {
-    strncpy(ifr.ifr_name, dev, IFNAMSIZ);
+    strncpy(ifr.ifr_name, dev, IFNAMSIZ - 1);
   }
 
   if( (err = ioctl(fd, TUNSETIFF, (void *)&ifr)) < 0 ) {
@@ -515,8 +513,8 @@ int main(int argc, char *argv[])
         serial_option = argv[3];
     }
 
-    char ifname[IFNAMSIZ];
-    strncpy(ifname, argv[1], IFNAMSIZ);
+    char ifname[IFNAMSIZ] = { 0 };
+    strncpy(ifname, argv[1], IFNAMSIZ - 1);
     int tap_fd = tun_alloc(ifname, IFF_TAP | IFF_NO_PI);
 
     if (tap_fd < 0) {