diff --git a/drivers/at86rf2xx/at86rf2xx_netdev.c b/drivers/at86rf2xx/at86rf2xx_netdev.c
index 4a5749418f..af853d722c 100644
--- a/drivers/at86rf2xx/at86rf2xx_netdev.c
+++ b/drivers/at86rf2xx/at86rf2xx_netdev.c
@@ -498,17 +498,17 @@ static int _set(netdev_t *netdev, netopt_t opt, const void *val, size_t len)
 
     switch (opt) {
         case NETOPT_ADDRESS:
-            assert(len <= sizeof(network_uint16_t));
+            assert(len == sizeof(network_uint16_t));
             at86rf2xx_set_addr_short(dev, val);
             /* don't set res to set netdev_ieee802154_t::short_addr */
             break;
         case NETOPT_ADDRESS_LONG:
-            assert(len <= sizeof(eui64_t));
+            assert(len == sizeof(eui64_t));
             at86rf2xx_set_addr_long(dev, val);
             /* don't set res to set netdev_ieee802154_t::long_addr */
             break;
         case NETOPT_NID:
-            assert(len <= sizeof(uint16_t));
+            assert(len == sizeof(uint16_t));
             at86rf2xx_set_pan(dev, *((const uint16_t *)val));
             /* don't set res to set netdev_ieee802154_t::pan */
             break;