diff --git a/node/IncomingPacket.cpp b/node/IncomingPacket.cpp
index 57d691b97..550ab3e5b 100644
--- a/node/IncomingPacket.cpp
+++ b/node/IncomingPacket.cpp
@@ -519,7 +519,8 @@ bool IncomingPacket::_doOK(const RuntimeEnvironment *RR,void *tPtr,const SharedP
 			if (network) {
 				const MulticastGroup mg(MAC(field(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_MAC,6),6),at<uint32_t>(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_ADI));
 				const unsigned int count = at<uint16_t>(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_GATHER_RESULTS + 4);
-				RR->mc->addMultiple(tPtr,RR->node->now(),networkId,mg,field(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_GATHER_RESULTS + 6,count * 5),count,at<uint32_t>(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_GATHER_RESULTS));
+				if (((ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_GATHER_RESULTS + 6) + (count * 5)) <= size())
+					RR->mc->addMultiple(tPtr,RR->node->now(),networkId,mg,field(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_GATHER_RESULTS + 6,count * 5),count,at<uint32_t>(ZT_PROTO_VERB_MULTICAST_GATHER__OK__IDX_GATHER_RESULTS));
 			}
 		}	break;