diff --git a/contrib/apps/ping/ping.c b/contrib/apps/ping/ping.c
index 429ab00b..143fb83e 100644
--- a/contrib/apps/ping/ping.c
+++ b/contrib/apps/ping/ping.c
@@ -152,7 +152,7 @@ ping_send(int s, const ip_addr_t *addr)
 #if LWIP_IPV4
   if(IP_IS_V4(addr)) {
     struct sockaddr_in *to4 = (struct sockaddr_in*)&to;
-    to4->sin_len    = sizeof(to4);
+    to4->sin_len    = sizeof(*to4);
     to4->sin_family = AF_INET;
     inet_addr_from_ip4addr(&to4->sin_addr, ip_2_ip4(addr));
   }
@@ -161,7 +161,7 @@ ping_send(int s, const ip_addr_t *addr)
 #if LWIP_IPV6
   if(IP_IS_V6(addr)) {
     struct sockaddr_in6 *to6 = (struct sockaddr_in6*)&to;
-    to6->sin6_len    = sizeof(to6);
+    to6->sin6_len    = sizeof(*to6);
     to6->sin6_family = AF_INET6;
     inet6_addr_from_ip6addr(&to6->sin6_addr, ip_2_ip6(addr));
   }