diff --git a/src/core/memp.c b/src/core/memp.c
index edbb982f..15852439 100644
--- a/src/core/memp.c
+++ b/src/core/memp.c
@@ -58,6 +58,7 @@
 #include "lwip/snmp_structs.h"
 #include "lwip/snmp_msg.h"
 #include "lwip/dns.h"
+#include "lwip/netdb.h"
 #include "netif/ppp/ppp.h"
 #include "netif/ppp/pppoe.h"
 #include "netif/ppp/pppol2tp.h"
diff --git a/src/include/lwip/dns.h b/src/include/lwip/dns.h
index e5530ef5..eb81c90a 100644
--- a/src/include/lwip/dns.h
+++ b/src/include/lwip/dns.h
@@ -70,13 +70,6 @@ extern "C" {
 #define DNS_RRCLASS_HS            4     /* Hesiod [Dyer 87] */
 #define DNS_RRCLASS_FLUSH         0x800 /* Flush bit */
 
-/* The size used for the next line is rather a hack, but it prevents including socket.h in all files
-   that include memp.h, and that would possibly break portability (since socket.h defines some types
-   and constants possibly already define by the OS).
-   Calculation rule:
-   sizeof(struct addrinfo) + sizeof(struct sockaddr_in) + DNS_MAX_NAME_LENGTH + 1 byte zero-termination */
-#define NETDB_ELEM_SIZE           (32 + 16 + DNS_MAX_NAME_LENGTH + 1)
-
 #if DNS_LOCAL_HOSTLIST
 /** struct used for local host-list */
 struct local_hostlist_entry {
diff --git a/src/include/lwip/netdb.h b/src/include/lwip/netdb.h
index c6039f7b..0a57dd4c 100644
--- a/src/include/lwip/netdb.h
+++ b/src/include/lwip/netdb.h
@@ -92,6 +92,8 @@ struct addrinfo {
 };
 #endif /* LWIP_DNS_API_DECLARE_STRUCTS */
 
+#define NETDB_ELEM_SIZE           (sizeof(struct addrinfo) + sizeof(struct sockaddr_in) + DNS_MAX_NAME_LENGTH + 1)
+
 #if LWIP_DNS_API_DECLARE_H_ERRNO
 /* application accessable error code set by the DNS API functions */
 extern int h_errno;