diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index f1f11e42..0b6d94db 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -393,7 +393,7 @@ ip_input(struct pbuf *p, struct netif *inp)
     if (p == NULL) {
       return ERR_OK;
     }
-    iphdr = p->payload;
+    iphdr = (struct ip_hdr *)p->payload;
 #else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
     pbuf_free(p);
     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
@@ -721,7 +721,7 @@ ip_output_hinted(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
 void
 ip_debug_print(struct pbuf *p)
 {
-  struct ip_hdr *iphdr = p->payload;
+  struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
   u8_t *payload;
 
   payload = (u8_t *)iphdr + IP_HLEN;
diff --git a/src/core/ipv4/ip_frag.c b/src/core/ipv4/ip_frag.c
index 2ed8d83b..948e74b1 100644
--- a/src/core/ipv4/ip_frag.c
+++ b/src/core/ipv4/ip_frag.c
@@ -267,11 +267,11 @@ ip_reass_enqueue_new_datagram(struct ip_hdr *fraghdr, int clen)
 {
   struct ip_reassdata* ipr;
   /* No matching previous fragment found, allocate a new reassdata struct */
-  ipr = memp_malloc(MEMP_REASSDATA);
+  ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
   if (ipr == NULL) {
 #if IP_REASS_FREE_OLDEST
     if (ip_reass_remove_oldest_datagram(fraghdr, clen) >= clen) {
-      ipr = memp_malloc(MEMP_REASSDATA);
+      ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
     }
     if (ipr == NULL)
 #endif /* IP_REASS_FREE_OLDEST */
@@ -666,7 +666,7 @@ ip_frag(struct pbuf *p, struct netif *netif, ip_addr_t *dest)
   rambuf->payload = LWIP_MEM_ALIGN((void *)buf);
 
   /* Copy the IP header in it */
-  iphdr = rambuf->payload;
+  iphdr = (struct ip_hdr *)rambuf->payload;
   SMEMCPY(iphdr, p->payload, IP_HLEN);
 #else /* IP_FRAG_USES_STATIC_BUF */
   original_iphdr = p->payload;