diff --git a/src/core/ipv4/igmp.c b/src/core/ipv4/igmp.c
index 3173221f..f3db5914 100644
--- a/src/core/ipv4/igmp.c
+++ b/src/core/ipv4/igmp.c
@@ -97,14 +97,13 @@ Steve Reynolds
 #include "string.h"
 
 static struct igmp_group *igmp_lookup_group(struct netif *ifp, const ip4_addr_t *addr);
-static err_t  igmp_remove_group(struct igmp_group *group);
-static void   igmp_timeout( struct igmp_group *group);
+static err_t  igmp_remove_group(struct netif* netif, struct igmp_group *group);
+static void   igmp_timeout(struct netif *netif, struct igmp_group *group);
 static void   igmp_start_timer(struct igmp_group *group, u8_t max_time);
 static void   igmp_delaying_member(struct igmp_group *group, u8_t maxresp);
 static err_t  igmp_ip_output_if(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest, struct netif *netif);
-static void   igmp_send(struct igmp_group *group, u8_t type);
+static void   igmp_send(struct netif *netif, struct igmp_group *group, u8_t type);
 
-struct igmp_group* igmp_group_list;
 static ip4_addr_t     allsystems;
 static ip4_addr_t     allrouters;
 
@@ -160,36 +159,24 @@ igmp_start(struct netif *netif)
 err_t
 igmp_stop(struct netif *netif)
 {
-  struct igmp_group *group = igmp_group_list;
-  struct igmp_group *prev  = NULL;
-  struct igmp_group *next;
+  struct igmp_group *group = netif_igmp_data(netif);
+
+  netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_IGMP, NULL);
 
-  /* look for groups joined on this interface further down the list */
   while (group != NULL) {
-    next = group->next;
-    /* is it a group joined on this interface? */
-    if (group->netif == netif) {
-      /* is it the first group of the list? */
-      if (group == igmp_group_list) {
-        igmp_group_list = next;
-      }
-      /* is there a "previous" group defined? */
-      if (prev != NULL) {
-        prev->next = next;
-      }
-      /* disable the group at the MAC level */
-      if (netif->igmp_mac_filter != NULL) {
-        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_stop: igmp_mac_filter(DEL "));
-        ip4_addr_debug_print(IGMP_DEBUG, &group->group_address);
-        LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", (void*)netif));
-        netif->igmp_mac_filter(netif, &(group->group_address), NETIF_DEL_MAC_FILTER);
-      }
-      /* free group */
-      memp_free(MEMP_IGMP_GROUP, group);
-    } else {
-      /* change the "previous" */
-      prev = group;
+    struct igmp_group *next = group->next; /* avoid use-after-free below */
+
+    /* disable the group at the MAC level */
+    if (netif->igmp_mac_filter != NULL) {
+      LWIP_DEBUGF(IGMP_DEBUG, ("igmp_stop: igmp_mac_filter(DEL "));
+      ip4_addr_debug_print(IGMP_DEBUG, &group->group_address);
+      LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", (void*)netif));
+      netif->igmp_mac_filter(netif, &(group->group_address), NETIF_DEL_MAC_FILTER);
     }
+
+    /* free group */
+    memp_free(MEMP_IGMP_GROUP, group);
+
     /* move to "next" */
     group = next;
   }
@@ -204,12 +191,12 @@ igmp_stop(struct netif *netif)
 void
 igmp_report_groups(struct netif *netif)
 {
-  struct igmp_group *group = igmp_group_list;
+  struct igmp_group *group = netif_igmp_data(netif);
 
   LWIP_DEBUGF(IGMP_DEBUG, ("igmp_report_groups: sending IGMP reports on if %p\n", (void*)netif));
 
   while (group != NULL) {
-    if ((group->netif == netif) && (!(ip4_addr_cmp(&(group->group_address), &allsystems)))) {
+    if (!(ip4_addr_cmp(&(group->group_address), &allsystems))) {
       igmp_delaying_member(group, IGMP_JOIN_DELAYING_MEMBER_TMR);
     }
     group = group->next;
@@ -227,10 +214,10 @@ igmp_report_groups(struct netif *netif)
 struct igmp_group *
 igmp_lookfor_group(struct netif *ifp, const ip4_addr_t *addr)
 {
-  struct igmp_group *group = igmp_group_list;
+  struct igmp_group *group = netif_igmp_data(ifp);
 
   while (group != NULL) {
-    if ((group->netif == ifp) && (ip4_addr_cmp(&(group->group_address), addr))) {
+    if (ip4_addr_cmp(&(group->group_address), addr)) {
       return group;
     }
     group = group->next;
@@ -265,15 +252,14 @@ igmp_lookup_group(struct netif *ifp, const ip4_addr_t *addr)
   /* Group doesn't exist yet, create a new one */
   group = (struct igmp_group *)memp_malloc(MEMP_IGMP_GROUP);
   if (group != NULL) {
-    group->netif              = ifp;
     ip4_addr_set(&(group->group_address), addr);
     group->timer              = 0; /* Not running */
     group->group_state        = IGMP_GROUP_NON_MEMBER;
     group->last_reporter_flag = 0;
     group->use                = 0;
-    group->next               = igmp_group_list;
+    group->next               = netif_igmp_data(ifp);
 
-    igmp_group_list = group;
+    netif_set_client_data(ifp, LWIP_NETIF_CLIENT_DATA_INDEX_IGMP, group);
   }
 
   LWIP_DEBUGF(IGMP_DEBUG, ("igmp_lookup_group: %sallocated a new group with address ", (group?"":"impossible to ")));
@@ -290,17 +276,17 @@ igmp_lookup_group(struct netif *ifp, const ip4_addr_t *addr)
  * @return ERR_OK if group was removed from the list, an err_t otherwise
  */
 static err_t
-igmp_remove_group(struct igmp_group *group)
+igmp_remove_group(struct netif* netif, struct igmp_group *group)
 {
   err_t err = ERR_OK;
 
   /* Is it the first group? */
-  if (igmp_group_list == group) {
-    igmp_group_list = group->next;
+  if (netif_igmp_data(netif) == group) {
+    netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_IGMP, group->next);
   } else {
     /* look for group further down the list */
     struct igmp_group *tmpGroup;
-    for (tmpGroup = igmp_group_list; tmpGroup != NULL; tmpGroup = tmpGroup->next) {
+    for (tmpGroup = netif_igmp_data(netif); tmpGroup != NULL; tmpGroup = tmpGroup->next) {
       if (tmpGroup->next == group) {
         tmpGroup->next = group->next;
         break;
@@ -381,10 +367,10 @@ igmp_input(struct pbuf *p, struct netif *inp, const ip4_addr_t *dest)
         IGMP_STATS_INC(igmp.rx_general);
       }
 
-      groupref = igmp_group_list;
+      groupref = netif_igmp_data(inp);
       while (groupref) {
         /* Do not send messages on the all systems group address! */
-        if ((groupref->netif == inp) && (!(ip4_addr_cmp(&(groupref->group_address), &allsystems)))) {
+        if (!(ip4_addr_cmp(&(groupref->group_address), &allsystems))) {
           igmp_delaying_member(groupref, igmp->igmp_maxresp);
         }
         groupref = groupref->next;
@@ -427,7 +413,7 @@ igmp_input(struct pbuf *p, struct netif *inp, const ip4_addr_t *dest)
     break;
   default:
     LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: unexpected msg %d in state %d on group %p on if %p\n",
-      igmp->igmp_msgtype, group->group_state, (void*)&group, (void*)group->netif));
+      igmp->igmp_msgtype, group->group_state, (void*)&group, (void*)inp));
     IGMP_STATS_INC(igmp.proterr);
     break;
   }
@@ -515,7 +501,7 @@ igmp_joingroup_netif(struct netif *netif, const ip4_addr_t *groupaddr)
       }
 
       IGMP_STATS_INC(igmp.tx_join);
-      igmp_send(group, IGMP_V2_MEMB_REPORT);
+      igmp_send(netif, group, IGMP_V2_MEMB_REPORT);
 
       igmp_start_timer(group, IGMP_JOIN_DELAYING_MEMBER_TMR);
 
@@ -600,13 +586,13 @@ igmp_leavegroup_netif(struct netif *netif, const ip4_addr_t *groupaddr)
     /* If there is no other use of the group */
     if (group->use <= 1) {
       /* Remove the group from the list */
-      igmp_remove_group(group);
+      igmp_remove_group(netif, group);
 
       /* If we are the last reporter for this group */
       if (group->last_reporter_flag) {
         LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup_netif: sending leaving group\n"));
         IGMP_STATS_INC(igmp.tx_leave);
-        igmp_send(group, IGMP_LEAVE_GROUP);
+        igmp_send(netif, group, IGMP_LEAVE_GROUP);
       }
 
       /* Disable the group at the MAC level */
@@ -637,16 +623,21 @@ igmp_leavegroup_netif(struct netif *netif, const ip4_addr_t *groupaddr)
 void
 igmp_tmr(void)
 {
-  struct igmp_group *group = igmp_group_list;
+  struct netif *netif = netif_list;
 
-  while (group != NULL) {
-    if (group->timer > 0) {
-      group->timer--;
-      if (group->timer == 0) {
-        igmp_timeout(group);
+  while (netif != NULL) {
+    struct igmp_group *group = netif_igmp_data(netif);
+
+    while (group != NULL) {
+      if (group->timer > 0) {
+        group->timer--;
+        if (group->timer == 0) {
+          igmp_timeout(netif, group);
+        }
       }
+      group = group->next;
     }
-    group = group->next;
+    netif = netif->next;
   }
 }
 
@@ -657,7 +648,7 @@ igmp_tmr(void)
  * @param group an igmp_group for which a timeout is reached
  */
 static void
-igmp_timeout(struct igmp_group *group)
+igmp_timeout(struct netif *netif, struct igmp_group *group)
 {
   /* If the state is IGMP_GROUP_DELAYING_MEMBER then we send a report for this group
      (unless it is the allsystems group) */
@@ -665,10 +656,10 @@ igmp_timeout(struct igmp_group *group)
       (!(ip4_addr_cmp(&(group->group_address), &allsystems)))) {
     LWIP_DEBUGF(IGMP_DEBUG, ("igmp_timeout: report membership for group with address "));
     ip4_addr_debug_print(IGMP_DEBUG, &(group->group_address));
-    LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", (void*)group->netif));
+    LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", (void*)netif));
 
     IGMP_STATS_INC(igmp.tx_report);
-    igmp_send(group, IGMP_V2_MEMB_REPORT);
+    igmp_send(netif, group, IGMP_V2_MEMB_REPORT);
   }
 }
 
@@ -748,7 +739,7 @@ igmp_ip_output_if(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
  * @param type the type of igmp packet to send
  */
 static void
-igmp_send(struct igmp_group *group, u8_t type)
+igmp_send(struct netif *netif, struct igmp_group *group, u8_t type)
 {
   struct pbuf*     p    = NULL;
   struct igmp_msg* igmp = NULL;
@@ -762,7 +753,7 @@ igmp_send(struct igmp_group *group, u8_t type)
     igmp = (struct igmp_msg *)p->payload;
     LWIP_ASSERT("igmp_send: check that first pbuf can hold struct igmp_msg",
                (p->len >= sizeof(struct igmp_msg)));
-    ip4_addr_copy(src, *netif_ip4_addr(group->netif));
+    ip4_addr_copy(src, *netif_ip4_addr(netif));
 
     if (type == IGMP_V2_MEMB_REPORT) {
       dest = &(group->group_address);
@@ -781,7 +772,7 @@ igmp_send(struct igmp_group *group, u8_t type)
       igmp->igmp_checksum = 0;
       igmp->igmp_checksum = inet_chksum(igmp, IGMP_MINLEN);
 
-      igmp_ip_output_if(p, &src, dest, group->netif);
+      igmp_ip_output_if(p, &src, dest, netif);
     }
 
     pbuf_free(p);
diff --git a/src/core/ipv6/mld6.c b/src/core/ipv6/mld6.c
index 0f92548d..c8910428 100644
--- a/src/core/ipv6/mld6.c
+++ b/src/core/ipv6/mld6.c
@@ -75,16 +75,11 @@
 #define MLD6_GROUP_DELAYING_MEMBER        1
 #define MLD6_GROUP_IDLE_MEMBER            2
 
-
-/* The list of joined groups. */
-struct mld_group* mld_group_list;
-
-
 /* Forward declarations. */
 static struct mld_group *mld6_new_group(struct netif *ifp, const ip6_addr_t *addr);
-static err_t mld6_remove_group(struct mld_group *group);
+static err_t mld6_remove_group(struct netif *netif, struct mld_group *group);
 static void mld6_delayed_report(struct mld_group *group, u16_t maxresp);
-static void mld6_send(struct mld_group *group, u8_t type);
+static void mld6_send(struct netif *netif, struct mld_group *group, u8_t type);
 
 
 /**
@@ -95,33 +90,21 @@ static void mld6_send(struct mld_group *group, u8_t type);
 err_t
 mld6_stop(struct netif *netif)
 {
-  struct mld_group *group = mld_group_list;
-  struct mld_group *prev  = NULL;
-  struct mld_group *next;
+  struct mld_group *group = netif_mld6_data(netif);
+
+  netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, NULL);
 
-  /* look for groups joined on this interface further down the list */
   while (group != NULL) {
-    next = group->next;
-    /* is it a group joined on this interface? */
-    if (group->netif == netif) {
-      /* is it the first group of the list? */
-      if (group == mld_group_list) {
-        mld_group_list = next;
-      }
-      /* is there a "previous" group defined? */
-      if (prev != NULL) {
-        prev->next = next;
-      }
-      /* disable the group at the MAC level */
-      if (netif->mld_mac_filter != NULL) {
-        netif->mld_mac_filter(netif, &(group->group_address), NETIF_DEL_MAC_FILTER);
-      }
-      /* free group */
-      memp_free(MEMP_MLD6_GROUP, group);
-    } else {
-      /* change the "previous" */
-      prev = group;
+    struct mld_group *next = group->next; /* avoid use-after-free below */
+
+    /* disable the group at the MAC level */
+    if (netif->mld_mac_filter != NULL) {
+      netif->mld_mac_filter(netif, &(group->group_address), NETIF_DEL_MAC_FILTER);
     }
+
+    /* free group */
+    memp_free(MEMP_MLD6_GROUP, group);
+
     /* move to "next" */
     group = next;
   }
@@ -136,12 +119,10 @@ mld6_stop(struct netif *netif)
 void
 mld6_report_groups(struct netif *netif)
 {
-  struct mld_group *group = mld_group_list;
+  struct mld_group *group = netif_mld6_data(netif);
 
   while (group != NULL) {
-    if (group->netif == netif) {
-      mld6_delayed_report(group, MLD6_JOIN_DELAYING_MEMBER_TMR_MS);
-    }
+    mld6_delayed_report(group, MLD6_JOIN_DELAYING_MEMBER_TMR_MS);
     group = group->next;
   }
 }
@@ -157,10 +138,10 @@ mld6_report_groups(struct netif *netif)
 struct mld_group *
 mld6_lookfor_group(struct netif *ifp, const ip6_addr_t *addr)
 {
-  struct mld_group *group = mld_group_list;
+  struct mld_group *group = netif_mld6_data(ifp);
 
   while (group != NULL) {
-    if ((group->netif == ifp) && (ip6_addr_cmp(&(group->group_address), addr))) {
+    if (ip6_addr_cmp(&(group->group_address), addr)) {
       return group;
     }
     group = group->next;
@@ -185,15 +166,14 @@ mld6_new_group(struct netif *ifp, const ip6_addr_t *addr)
 
   group = (struct mld_group *)memp_malloc(MEMP_MLD6_GROUP);
   if (group != NULL) {
-    group->netif              = ifp;
     ip6_addr_set(&(group->group_address), addr);
     group->timer              = 0; /* Not running */
     group->group_state        = MLD6_GROUP_IDLE_MEMBER;
     group->last_reporter_flag = 0;
     group->use                = 0;
-    group->next               = mld_group_list;
+    group->next               = netif_mld6_data(ifp);
 
-    mld_group_list = group;
+    netif_set_client_data(ifp, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, group);
   }
 
   return group;
@@ -206,17 +186,17 @@ mld6_new_group(struct netif *ifp, const ip6_addr_t *addr)
  * @return ERR_OK if group was removed from the list, an err_t otherwise
  */
 static err_t
-mld6_remove_group(struct mld_group *group)
+mld6_remove_group(struct netif *netif, struct mld_group *group)
 {
   err_t err = ERR_OK;
 
   /* Is it the first group? */
-  if (mld_group_list == group) {
-    mld_group_list = group->next;
+  if (netif_mld6_data(netif) == group) {
+    netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, group->next);
   } else {
     /* look for group further down the list */
     struct mld_group *tmpGroup;
-    for (tmpGroup = mld_group_list; tmpGroup != NULL; tmpGroup = tmpGroup->next) {
+    for (tmpGroup = netif_mld6_data(netif); tmpGroup != NULL; tmpGroup = tmpGroup->next) {
       if (tmpGroup->next == group) {
         tmpGroup->next = group->next;
         break;
@@ -264,10 +244,9 @@ mld6_input(struct pbuf *p, struct netif *inp)
         ip6_addr_isany(&(mld_hdr->multicast_address))) {
       MLD6_STATS_INC(mld6.rx_general);
       /* Report all groups, except all nodes group, and if-local groups. */
-      group = mld_group_list;
+      group = netif_mld6_data(inp);
       while (group != NULL) {
-        if ((group->netif == inp) &&
-            (!(ip6_addr_ismulticast_iflocal(&(group->group_address)))) &&
+        if ((!(ip6_addr_ismulticast_iflocal(&(group->group_address)))) &&
             (!(ip6_addr_isallnodes_linklocal(&(group->group_address))))) {
           mld6_delayed_report(group, mld_hdr->max_resp_delay);
         }
@@ -376,7 +355,7 @@ mld6_joingroup_netif(struct netif *netif, const ip6_addr_t *groupaddr)
 
     /* Report our membership. */
     MLD6_STATS_INC(mld6.tx_report);
-    mld6_send(group, ICMP6_TYPE_MLR);
+    mld6_send(netif, group, ICMP6_TYPE_MLR);
     mld6_delayed_report(group, MLD6_JOIN_DELAYING_MEMBER_TMR_MS);
   }
 
@@ -439,12 +418,12 @@ mld6_leavegroup_netif(struct netif *netif, const ip6_addr_t *groupaddr)
     /* Leave if there is no other use of the group */
     if (group->use <= 1) {
       /* Remove the group from the list */
-      mld6_remove_group(group);
+      mld6_remove_group(netif, group);
 
       /* If we are the last reporter for this group */
       if (group->last_reporter_flag) {
         MLD6_STATS_INC(mld6.tx_leave);
-        mld6_send(group, ICMP6_TYPE_MLD);
+        mld6_send(netif, group, ICMP6_TYPE_MLD);
       }
 
       /* Disable the group at the MAC level */
@@ -477,21 +456,25 @@ mld6_leavegroup_netif(struct netif *netif, const ip6_addr_t *groupaddr)
 void
 mld6_tmr(void)
 {
-  struct mld_group *group = mld_group_list;
+  struct netif *netif = netif_list;
 
-  while (group != NULL) {
-    if (group->timer > 0) {
-      group->timer--;
-      if (group->timer == 0) {
-        /* If the state is MLD6_GROUP_DELAYING_MEMBER then we send a report for this group */
-        if (group->group_state == MLD6_GROUP_DELAYING_MEMBER) {
-          MLD6_STATS_INC(mld6.tx_report);
-          mld6_send(group, ICMP6_TYPE_MLR);
-          group->group_state = MLD6_GROUP_IDLE_MEMBER;
+  while (netif != NULL) {
+    struct mld_group *group = netif_mld6_data(netif);
+
+    while (group != NULL) {
+      if (group->timer > 0) {
+        group->timer--;
+        if (group->timer == 0) {
+          /* If the state is MLD6_GROUP_DELAYING_MEMBER then we send a report for this group */
+          if (group->group_state == MLD6_GROUP_DELAYING_MEMBER) {
+            MLD6_STATS_INC(mld6.tx_report);
+            mld6_send(netif, group, ICMP6_TYPE_MLR);
+            group->group_state = MLD6_GROUP_IDLE_MEMBER;
+          }
         }
       }
+      group = group->next;
     }
-    group = group->next;
   }
 }
 
@@ -538,7 +521,7 @@ mld6_delayed_report(struct mld_group *group, u16_t maxresp)
  * @param type ICMP6_TYPE_MLR (report) or ICMP6_TYPE_MLD (done)
  */
 static void
-mld6_send(struct mld_group *group, u8_t type)
+mld6_send(struct netif *netif, struct mld_group *group, u8_t type)
 {
   struct mld_header *mld_hdr;
   struct pbuf *p;
@@ -559,13 +542,13 @@ mld6_send(struct mld_group *group, u8_t type)
   }
 
   /* Select our source address. */
-  if (!ip6_addr_isvalid(netif_ip6_addr_state(group->netif, 0))) {
+  if (!ip6_addr_isvalid(netif_ip6_addr_state(netif, 0))) {
     /* This is a special case, when we are performing duplicate address detection.
      * We must join the multicast group, but we don't have a valid address yet. */
     src_addr = IP6_ADDR_ANY6;
   } else {
     /* Use link-local address as source address. */
-    src_addr = netif_ip6_addr(group->netif, 0);
+    src_addr = netif_ip6_addr(netif, 0);
   }
 
   /* MLD message header pointer. */
@@ -592,7 +575,7 @@ mld6_send(struct mld_group *group, u8_t type)
   /* Send the packet out. */
   MLD6_STATS_INC(mld6.xmit);
   ip6_output_if(p, (ip6_addr_isany(src_addr)) ? NULL : src_addr, &(group->group_address),
-      MLD6_HL, 0, IP6_NEXTH_HOPBYHOP, group->netif);
+      MLD6_HL, 0, IP6_NEXTH_HOPBYHOP, netif);
   pbuf_free(p);
 }
 
diff --git a/src/core/netif.c b/src/core/netif.c
index 819b4ecc..7ea44829 100644
--- a/src/core/netif.c
+++ b/src/core/netif.c
@@ -259,7 +259,7 @@ netif_add(struct netif *netif,
 #endif /* LWIP_IPV6 */
   NETIF_SET_CHECKSUM_CTRL(netif, NETIF_CHECKSUM_ENABLE_ALL);
   netif->flags = 0;
-#if LWIP_DHCP || LWIP_AUTOIP || (LWIP_NUM_NETIF_CLIENT_DATA > 0)
+#ifdef netif_get_client_data
   memset(netif->client_data, 0, sizeof(netif->client_data));
 #endif /* LWIP_NUM_NETIF_CLIENT_DATA */
 #if LWIP_IPV6_AUTOCONFIG
diff --git a/src/include/lwip/igmp.h b/src/include/lwip/igmp.h
index 6b46bbcc..ba9986b2 100644
--- a/src/include/lwip/igmp.h
+++ b/src/include/lwip/igmp.h
@@ -74,8 +74,6 @@ extern "C" {
 struct igmp_group {
   /** next link */
   struct igmp_group *next;
-  /** interface on which the group is active */
-  struct netif      *netif;
   /** multicast address */
   ip4_addr_t         group_address;
   /** signifies we were the last person to report */
@@ -88,9 +86,6 @@ struct igmp_group {
   u8_t               use;
 };
 
-/* Head of IGMP group list */
-extern struct igmp_group* igmp_group_list;
-
 /*  Prototypes */
 void   igmp_init(void);
 err_t  igmp_start(struct netif *netif);
@@ -104,6 +99,9 @@ err_t  igmp_leavegroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr);
 err_t  igmp_leavegroup_netif(struct netif *netif, const ip4_addr_t *groupaddr);
 void   igmp_tmr(void);
 
+/* Get list of IGMP groups for netif */
+#define netif_igmp_data(netif) ((struct igmp_group *)netif_get_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_IGMP))
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/include/lwip/mld6.h b/src/include/lwip/mld6.h
index 02637e8b..eebab250 100644
--- a/src/include/lwip/mld6.h
+++ b/src/include/lwip/mld6.h
@@ -58,8 +58,6 @@ extern "C" {
 struct mld_group {
   /** next link */
   struct mld_group *next;
-  /** interface on which the group is active */
-  struct netif      *netif;
   /** multicast address */
   ip6_addr_t         group_address;
   /** signifies we were the last person to report */
@@ -72,9 +70,6 @@ struct mld_group {
   u8_t               use;
 };
 
-/* Head of MLD group list */
-extern struct mld_group* mld_group_list;
-
 #define MLD6_TMR_INTERVAL              100 /* Milliseconds */
 
 err_t  mld6_stop(struct netif *netif);
@@ -87,6 +82,9 @@ err_t  mld6_joingroup_netif(struct netif *netif, const ip6_addr_t *groupaddr);
 err_t  mld6_leavegroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr);
 err_t  mld6_leavegroup_netif(struct netif *netif, const ip6_addr_t *groupaddr);
 
+/* Get list of MLD6 groups for netif */
+#define netif_mld6_data(netif) ((struct mld_group *)netif_get_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6))
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/include/lwip/netif.h b/src/include/lwip/netif.h
index 0b2bfab3..1d19b27a 100644
--- a/src/include/lwip/netif.h
+++ b/src/include/lwip/netif.h
@@ -111,6 +111,12 @@ enum lwip_internal_netif_client_data_index
 #endif
 #if LWIP_AUTOIP
    LWIP_NETIF_CLIENT_DATA_INDEX_AUTOIP,
+#endif
+#if LWIP_IGMP
+   LWIP_NETIF_CLIENT_DATA_INDEX_IGMP,
+#endif
+#if LWIP_IPV6_MLD
+   LWIP_NETIF_CLIENT_DATA_INDEX_MLD6,
 #endif
    LWIP_NETIF_CLIENT_DATA_INDEX_MAX
 };
@@ -201,6 +207,18 @@ typedef err_t (*netif_mld_mac_filter_fn)(struct netif *netif,
        const ip6_addr_t *group, enum netif_mac_filter_action action);
 #endif /* LWIP_IPV6 && LWIP_IPV6_MLD */
 
+#if LWIP_DHCP || LWIP_AUTOIP || LWIP_IGMP || LWIP_IPV6_MLD || (LWIP_NUM_NETIF_CLIENT_DATA > 0)
+u8_t netif_alloc_client_data_id(void);
+/** @ingroup netif_cd
+ * Set client data. Obtain ID from netif_alloc_client_data_id().
+ */
+#define netif_set_client_data(netif, id, data) netif_get_client_data(netif, id) = (data)
+/** @ingroup netif_cd
+ * Get client data. Obtain ID from netif_alloc_client_data_id().
+ */
+#define netif_get_client_data(netif, id)       (netif)->client_data[(id)]
+#endif /* LWIP_DHCP || LWIP_AUTOIP || (LWIP_NUM_NETIF_CLIENT_DATA > 0) */
+
 /** Generic data structure used for all lwIP network interfaces.
  *  The following fields should be filled in by the initialization
  *  function for the device driver: hwaddr_len, hwaddr[], mtu, flags */
@@ -257,7 +275,7 @@ struct netif {
   /** This field can be set by the device driver and could point
    *  to state information for the device. */
   void *state;
-#if LWIP_DHCP || LWIP_AUTOIP || (LWIP_NUM_NETIF_CLIENT_DATA > 0)
+#ifdef netif_get_client_data
   void* client_data[LWIP_NETIF_CLIENT_DATA_INDEX_MAX + LWIP_NUM_NETIF_CLIENT_DATA];
 #endif
 #if LWIP_IPV6_AUTOCONFIG
@@ -424,18 +442,6 @@ void netif_poll_all(void);
 
 err_t netif_input(struct pbuf *p, struct netif *inp);
 
-#if LWIP_DHCP || LWIP_AUTOIP || (LWIP_NUM_NETIF_CLIENT_DATA > 0)
-u8_t netif_alloc_client_data_id(void);
-/** @ingroup netif_cd
- * Set client data. Obtain ID from netif_alloc_client_data_id().
- */
-#define netif_set_client_data(netif, id, data) netif_get_client_data(netif, id) = (data)
-/** @ingroup netif_cd
- * Get client data. Obtain ID from netif_alloc_client_data_id().
- */
-#define netif_get_client_data(netif, id)       (netif)->client_data[(id)]
-#endif /* LWIP_DHCP || LWIP_AUTOIP || (LWIP_NUM_NETIF_CLIENT_DATA > 0) */
-
 #if LWIP_IPV6
 /** @ingroup netif_ip6 */
 #define netif_ip_addr6(netif, i)  ((const ip_addr_t*)(&((netif)->ip6_addr[i])))