diff --git a/src/core/snmp/mib2.c b/src/core/snmp/mib2.c
index 9479a12d..11a055ee 100644
--- a/src/core/snmp/mib2.c
+++ b/src/core/snmp/mib2.c
@@ -833,7 +833,7 @@ void mib2_add_arp_entry(struct netif *ni, ip4_addr_t *ip)
         }
         else
         {
-          at_rn = (struct mib_list_rootnode*)at_node->nptr;
+          at_rn = (struct mib_list_rootnode*)(void*)at_node->nptr;
         }
       }
     }
@@ -884,13 +884,13 @@ void mib2_remove_arp_entry(struct netif *ni, ip4_addr_t *ip)
         del_rn[del_cnt] = at_rn;
         del_n[del_cnt] = at_n;
         del_cnt++;
-        at_rn = (struct mib_list_rootnode*)(at_n->nptr);
+        at_rn = (struct mib_list_rootnode*)(void*)at_n->nptr;
       }
       else if (fc == 2)
       {
         /* reset delete (2 or more childs) */
         del_cnt = 0;
-        at_rn = (struct mib_list_rootnode*)(at_n->nptr);
+        at_rn = (struct mib_list_rootnode*)(void*)at_n->nptr;
       }
       level++;
     }
@@ -960,7 +960,7 @@ void mib2_add_ip4(struct netif *ni)
       }
       else
       {
-        ipa_rn = (struct mib_list_rootnode*)ipa_node->nptr;
+        ipa_rn = (struct mib_list_rootnode*)(void*)ipa_node->nptr;
       }
     }
     level++;
@@ -1001,13 +1001,13 @@ void mib2_remove_ip4(struct netif *ni)
       del_rn[del_cnt] = ipa_rn;
       del_n[del_cnt] = ipa_n;
       del_cnt++;
-      ipa_rn = (struct mib_list_rootnode*)(ipa_n->nptr);
+      ipa_rn = (struct mib_list_rootnode*)(void*)ipa_n->nptr;
     }
     else if (fc == 2)
     {
       /* reset delete (2 or more childs) */
       del_cnt = 0;
-      ipa_rn = (struct mib_list_rootnode*)(ipa_n->nptr);
+      ipa_rn = (struct mib_list_rootnode*)(void*)ipa_n->nptr;
     }
     level++;
   }
@@ -1099,7 +1099,7 @@ void mib2_add_route_ip4(u8_t dflt, struct netif *ni)
         }
         else
         {
-          iprte_rn = (struct mib_list_rootnode*)iprte_node->nptr;
+          iprte_rn = (struct mib_list_rootnode*)(void*)iprte_node->nptr;
         }
       }
       level++;
@@ -1163,13 +1163,13 @@ void mib2_remove_route_ip4(u8_t dflt, struct netif *ni)
         del_rn[del_cnt] = iprte_rn;
         del_n[del_cnt] = iprte_n;
         del_cnt++;
-        iprte_rn = (struct mib_list_rootnode*)(iprte_n->nptr);
+        iprte_rn = (struct mib_list_rootnode*)(void*)iprte_n->nptr;
       }
       else if (fc == 2)
       {
         /* reset delete (2 or more childs) */
         del_cnt = 0;
-        iprte_rn = (struct mib_list_rootnode*)(iprte_n->nptr);
+        iprte_rn = (struct mib_list_rootnode*)(void*)iprte_n->nptr;
       }
       level++;
     }
@@ -1243,7 +1243,7 @@ void mib2_udp_bind(struct udp_pcb *pcb)
       }
       else
       {
-        udp_rn = (struct mib_list_rootnode*)udp_node->nptr;
+        udp_rn = (struct mib_list_rootnode*)(void*)udp_node->nptr;
       }
     }
   }
@@ -1304,13 +1304,13 @@ void mib2_udp_unbind(struct udp_pcb *pcb)
         del_rn[del_cnt] = udp_rn;
         del_n[del_cnt] = udp_n;
         del_cnt++;
-        udp_rn = (struct mib_list_rootnode*)(udp_n->nptr);
+        udp_rn = (struct mib_list_rootnode*)(void*)udp_n->nptr;
       }
       else if (fc == 2)
       {
         /* reset delete (2 or more childs) */
         del_cnt = 0;
-        udp_rn = (struct mib_list_rootnode*)(udp_n->nptr);
+        udp_rn = (struct mib_list_rootnode*)(void*)udp_n->nptr;
       }
       level++;
     }
diff --git a/src/core/snmp/mib_structs.c b/src/core/snmp/mib_structs.c
index 60012737..10e85f2c 100644
--- a/src/core/snmp/mib_structs.c
+++ b/src/core/snmp/mib_structs.c
@@ -361,7 +361,7 @@ snmp_mib_node_find(struct mib_list_rootnode *rn, s32_t objid, struct mib_list_no
 
     if (n->nptr->node_type == MIB_NODE_LR)
     {
-      r = (struct mib_list_rootnode *)n->nptr;
+      r = (struct mib_list_rootnode*)(void*)n->nptr;
       if (r->count > 1)
       {
         /* can't delete node */
@@ -400,7 +400,7 @@ snmp_mib_node_delete(struct mib_list_rootnode *rn, struct mib_list_node *n)
   LWIP_ASSERT("n != NULL",n != NULL);
 
   /* caller must remove this sub-tree */
-  next = (struct mib_list_rootnode*)(n->nptr);
+  next = (struct mib_list_rootnode*)(void*)n->nptr;
   rn->count -= 1;
 
   if (n == rn->head)
@@ -466,7 +466,7 @@ snmp_search_tree(const struct mib_node *node, u8_t ident_len, s32_t *ident, stru
       if (ident_len > 0)
       {
         /* array node (internal ROM or RAM, fixed length) */
-        an = (const struct mib_array_node *)node;
+        an = (const struct mib_array_node*)(const void*)node;
         i = 0;
         while ((i < an->maxlength) && (an->entries[i].objid != *ident))
         {
@@ -514,7 +514,7 @@ snmp_search_tree(const struct mib_node *node, u8_t ident_len, s32_t *ident, stru
       if (ident_len > 0)
       {
         /* list root node (internal 'RAM', variable length) */
-        lrn = (const struct mib_list_rootnode *)node;
+        lrn = (const struct mib_list_rootnode*)(const void*)node;
         ln = lrn->head;
         /* iterate over list, head to tail */
         while ((ln != NULL) && (ln->objid != *ident))
@@ -561,7 +561,7 @@ snmp_search_tree(const struct mib_node *node, u8_t ident_len, s32_t *ident, stru
       if (ident_len > 0)
       {
         /* external node (addressing and access via functions) */
-        en = (const struct mib_external_node *)node;
+        en = (const struct mib_external_node*)(const void*)node;
 
         i = 0;
         len = en->level_length(en->addr_inf,ext_level);
@@ -646,7 +646,7 @@ empty_table(const struct mib_node *node)
     if (node_type == MIB_NODE_LR)
     {
       const struct mib_list_rootnode *lrn;
-      lrn = (const struct mib_list_rootnode *)node;
+      lrn = (const struct mib_list_rootnode*)(const void*)node;
       if ((lrn->count == 0) || (lrn->head == NULL))
       {
         empty = 1;
@@ -655,7 +655,7 @@ empty_table(const struct mib_node *node)
     else if ((node_type == MIB_NODE_AR) || (node_type == MIB_NODE_RA))
     {
       const struct mib_array_node *an;
-      an = (const struct mib_array_node *)node;
+      an = (const struct mib_array_node*)(const void*)node;
       if ((an->maxlength == 0) || (an->entries == NULL))
       {
         empty = 1;
@@ -664,7 +664,7 @@ empty_table(const struct mib_node *node)
     else if (node_type == MIB_NODE_EX)
     {
       const struct mib_external_node *en;
-      en = (const struct mib_external_node *)node;
+      en = (const struct mib_external_node*)(const void*)node;
       if (en->tree_levels == 0)
       {
         empty = 1;
@@ -695,7 +695,7 @@ snmp_expand_tree(const struct mib_node *node, u8_t ident_len, s32_t *ident, stru
       u16_t i;
 
       /* array node (internal ROM or RAM, fixed length) */
-      an = (const struct mib_array_node *)node;
+      an = (const struct mib_array_node*)(const void*)node;
       if (ident_len > 0)
       {
         i = 0;
@@ -815,7 +815,7 @@ snmp_expand_tree(const struct mib_node *node, u8_t ident_len, s32_t *ident, stru
       struct mib_list_node *ln;
 
       /* list root node (internal 'RAM', variable length) */
-      lrn = (const struct mib_list_rootnode *)node;
+      lrn = (const struct mib_list_rootnode*)(const void*)node;
       if (ident_len > 0)
       {
         ln = lrn->head;
@@ -933,7 +933,7 @@ snmp_expand_tree(const struct mib_node *node, u8_t ident_len, s32_t *ident, stru
       s32_t ex_id;
 
       /* external node (addressing and access via functions) */
-      en = (const struct mib_external_node *)node;
+      en = (const struct mib_external_node*)(const void*)node;
       if (ident_len > 0)
       {
         u16_t i, len;
diff --git a/src/core/snmp/msg_in.c b/src/core/snmp/msg_in.c
index 3e4587ce..85bfc288 100644
--- a/src/core/snmp/msg_in.c
+++ b/src/core/snmp/msg_in.c
@@ -351,7 +351,7 @@ snmp_msg_get_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
         if (mn->node_type == MIB_NODE_EX)
         {
           /* external object */
-          const struct mib_external_node *en = (const struct mib_external_node*)mn;
+          const struct mib_external_node *en = (const struct mib_external_node*)(const void*)mn;
 
           msg_ps->state = SNMP_MSG_EXTERNAL_GET_OBJDEF;
           /* save en && args in msg_ps!! */
@@ -364,7 +364,7 @@ snmp_msg_get_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
         {
           /* internal object */
           struct obj_def object_def;
-          const struct mib_scalar_node *msn = (const struct mib_scalar_node*)mn;
+          const struct mib_scalar_node *msn = (const struct mib_scalar_node*)(const void*)mn;
 
           msg_ps->state = SNMP_MSG_INTERNAL_GET_OBJDEF;
           msn->get_object_def(np.ident_len, np.ident, &object_def);
@@ -541,7 +541,7 @@ snmp_msg_getnext_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
       if (mn->node_type == MIB_NODE_EX)
       {
         /* external object */
-        const struct mib_external_node *en = (const struct mib_external_node*)mn;
+        const struct mib_external_node *en = (const struct mib_external_node*)(const void*)mn;
 
         msg_ps->state = SNMP_MSG_EXTERNAL_GET_OBJDEF;
         /* save en && args in msg_ps!! */
@@ -555,7 +555,7 @@ snmp_msg_getnext_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
         /* internal object */
         struct obj_def object_def;
         struct snmp_varbind *vb;
-        const struct mib_scalar_node *msn = (const struct mib_scalar_node*)mn;
+        const struct mib_scalar_node *msn = (const struct mib_scalar_node*)(const void*)mn;
 
         msg_ps->state = SNMP_MSG_INTERNAL_GET_OBJDEF;
         msn->get_object_def(1, &oid.id[oid.len - 1], &object_def);
@@ -720,7 +720,7 @@ snmp_msg_set_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
         if (mn->node_type == MIB_NODE_EX)
         {
           /* external object */
-          const struct mib_external_node *en = (const struct mib_external_node*)mn;
+          const struct mib_external_node *en = (const struct mib_external_node*)(const void*)mn;
 
           msg_ps->state = SNMP_MSG_EXTERNAL_GET_OBJDEF;
           /* save en && args in msg_ps!! */
@@ -733,7 +733,7 @@ snmp_msg_set_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
         {
           /* internal object */
           struct obj_def object_def;
-          const struct mib_scalar_node *msn = (const struct mib_scalar_node*)mn;
+          const struct mib_scalar_node *msn = (const struct mib_scalar_node*)(const void*)mn;
 
           msg_ps->state = SNMP_MSG_INTERNAL_GET_OBJDEF;
           msn->get_object_def(np.ident_len, np.ident, &object_def);
@@ -816,7 +816,7 @@ snmp_msg_set_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
       if (mn->node_type == MIB_NODE_EX)
       {
         /* external object */
-        const struct mib_external_node *en = (const struct mib_external_node*)mn;
+        const struct mib_external_node *en = (const struct mib_external_node*)(const void*)mn;
 
         msg_ps->state = SNMP_MSG_EXTERNAL_GET_OBJDEF_S;
         /* save en && args in msg_ps!! */
@@ -829,7 +829,7 @@ snmp_msg_set_event(u8_t request_id, struct snmp_msg_pstat *msg_ps)
       {
         /* internal object */
         struct obj_def object_def;
-        const struct mib_scalar_node *msn = (const struct mib_scalar_node*)mn;
+        const struct mib_scalar_node *msn = (const struct mib_scalar_node*)(const void*)mn;
 
         msg_ps->state = SNMP_MSG_INTERNAL_GET_OBJDEF_S;
         msn->get_object_def(np.ident_len, np.ident, &object_def);