diff --git a/extmod/extmod.mk b/extmod/extmod.mk
index 909952cc28142cf10541ab705acd924d88aafa45..05d0be3b1675c155bee048317da5a838fa5d7348 100644
--- a/extmod/extmod.mk
+++ b/extmod/extmod.mk
@@ -117,6 +117,7 @@ CFLAGS_MOD += -DMICROPY_PY_LWIP=1
 $(BUILD)/$(LWIP_DIR)/core/ipv4/dhcp.o: CFLAGS_MOD += -Wno-address
 SRC_MOD += extmod/modlwip.c lib/netutils/netutils.c
 SRC_MOD += $(addprefix $(LWIP_DIR)/,\
+	apps/mdns/mdns.c \
 	core/def.c \
 	core/dns.c \
 	core/inet_chksum.c \