diff --git a/net/icmpv6/icmpv6_input.c b/net/icmpv6/icmpv6_input.c
index 28792be0ca1..f7572e8d8a3 100644
--- a/net/icmpv6/icmpv6_input.c
+++ b/net/icmpv6/icmpv6_input.c
@@ -481,7 +481,8 @@ void icmpv6_input(FAR struct net_driver_s *dev, unsigned int iplen)
                   {
                     FAR struct icmpv6_mtu_s *mtuopt =
                                         (FAR struct icmpv6_mtu_s *)opt;
-                    dev->d_pktsize = NTOHS(mtuopt->mtu[1]) + dev->d_llhdrlen;
+                    dev->d_pktsize = MIN(dev->d_pktsize,
+                        NTOHS(mtuopt->mtu[1]) + dev->d_llhdrlen);
                   }
                   break;