diff --git a/raw.c b/raw.c
index 8b7bcf1..d9a3468 100644
--- a/raw.c
+++ b/raw.c
@@ -103,6 +103,7 @@ static int raw_configure(int fd, int event, int index,
 
 	option = enable ? PACKET_ADD_MEMBERSHIP : PACKET_DROP_MEMBERSHIP;
 
+	memset(&mreq, 0, sizeof(mreq));
 	mreq.mr_ifindex = index;
 	mreq.mr_type = PACKET_MR_MULTICAST;
 	mreq.mr_alen = MAC_LEN;