diff --git a/tests/host/common/MockWiFiServerSocket.cpp b/tests/host/common/MockWiFiServerSocket.cpp
index f56b9f424..ed3a13353 100644
--- a/tests/host/common/MockWiFiServerSocket.cpp
+++ b/tests/host/common/MockWiFiServerSocket.cpp
@@ -67,8 +67,8 @@ void WiFiServer::begin (uint16_t port, uint8_t backlog)
 {
     if (!backlog)
         return;
-	_port = port;
-	return begin();
+    _port = port;
+    return begin();
 }
 
 void WiFiServer::begin ()
diff --git a/tests/host/common/MocklwIP.cpp b/tests/host/common/MocklwIP.cpp
index f114572c1..8628cc47b 100644
--- a/tests/host/common/MocklwIP.cpp
+++ b/tests/host/common/MocklwIP.cpp
@@ -33,4 +33,31 @@ err_t etharp_request(struct netif *netif, const ip4_addr_t *ipaddr)
     return ERR_OK;
 }
 
+err_t igmp_start(struct netif* netif)
+{
+    (void)netif;
+    return ERR_OK;
+}
+
+err_t igmp_joingroup_netif(struct netif *netif, const ip4_addr_t *groupaddr)
+{
+    (void)netif;
+    (void)groupaddr;
+    return ERR_OK;
+}
+
+err_t igmp_leavegroup_netif(struct netif *netif, const ip4_addr_t *groupaddr)
+{
+    (void)netif;
+    (void)groupaddr;
+    return ERR_OK;
+}
+
+struct netif* netif_get_by_index(u8_t idx)
+{
+    (void)idx;
+    return &netif0;
+}
+
+
 } // extern "C"
diff --git a/tests/host/common/include/UdpContext.h b/tests/host/common/include/UdpContext.h
index ab7c2a97d..c4a87c19b 100644
--- a/tests/host/common/include/UdpContext.h
+++ b/tests/host/common/include/UdpContext.h
@@ -28,6 +28,8 @@ class UdpContext;
 #define GET_IP_HDR(pb) reinterpret_cast<ip_hdr*>(((uint8_t*)((pb)->payload)) - UDP_HLEN - IP_HLEN);
 #define GET_UDP_HDR(pb) reinterpret_cast<udp_hdr*>(((uint8_t*)((pb)->payload)) - UDP_HLEN);
 
+extern netif netif0;
+
 class UdpContext
 {
 public:
@@ -86,12 +88,24 @@ public:
         _dst.addr = staticMCastAddr;
     }
 
+    void setMulticastInterface(netif* p_pNetIf)
+    {
+        (void)p_pNetIf;
+        // user multicast, and this is how it works with posix: send to multicast address:
+        _dst.addr = staticMCastAddr;
+    }
+
     void setMulticastTTL(int ttl)
     {
         (void)ttl;
         //mockverbose("TODO: UdpContext::setMulticastTTL\n");
     }
 
+    netif* getInputNetif() const
+    {
+        return &netif0;
+    }
+
     // warning: handler is called from tcp stack context
     // esp_yield and non-reentrant functions which depend on it will fail
     void onRx(rxhandler_t handler) {
@@ -246,7 +260,7 @@ private:
     uint8_t addr[16];
 };
 
-inline err_t igmp_joingroup (const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
+extern "C" inline err_t igmp_joingroup (const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
 {
     (void)ifaddr;
     UdpContext::staticMCastAddr = groupaddr->addr;
diff --git a/tests/host/sys/pgmspace.h b/tests/host/sys/pgmspace.h
index 1b357d2e3..69a3b4fd9 100644
--- a/tests/host/sys/pgmspace.h
+++ b/tests/host/sys/pgmspace.h
@@ -67,5 +67,6 @@ inline int vsnprintf_P(char *str, size_t size, const char *format, va_list ap) {
 #define snprintf_P snprintf
 #define sprintf_P sprintf
 #define strncmp_P strncmp
+#define strcat_P strcat
 
 #endif