diff --git a/magneticod/bittorrent/sinkMetadata.go b/magneticod/bittorrent/sinkMetadata.go
index 55842f3..2d7ff32 100644
--- a/magneticod/bittorrent/sinkMetadata.go
+++ b/magneticod/bittorrent/sinkMetadata.go
@@ -32,6 +32,7 @@ type MetadataSink struct {
 	clientID    []byte
 	deadline    time.Duration
 	drain       chan Metadata
+	incomingInfoHashes map[[20]byte]struct{}
 	terminated  bool
 	termination chan interface{}
 }
@@ -44,13 +45,9 @@ func NewMetadataSink(deadline time.Duration) *MetadataSink {
 	if err != nil {
 		zap.L().Panic("sinkMetadata couldn't read 20 random bytes for client ID!", zap.Error(err))
 	}
-	// TODO: remove this
-	if len(ms.clientID) != 20 {
-		panic("CLIENT ID NOT 20!")
-	}
-
 	ms.deadline = deadline
 	ms.drain = make(chan Metadata)
+	ms.incomingInfoHashes = make(map[[20]byte]struct{})
 	ms.termination = make(chan interface{})
 	return ms
 }
@@ -60,6 +57,15 @@ func (ms *MetadataSink) Sink(res mainline.TrawlingResult) {
 		zap.L().Panic("Trying to Sink() an already closed MetadataSink!")
 	}
 
+	if _, exists := ms.incomingInfoHashes[res.InfoHash]; exists {
+		return
+	}
+	// BEWARE!
+	// Although not crucial, the assumption is that MetadataSink.Sink() will be called by only one
+	// goroutine (i.e. it's not thread-safe), lest there might be a race condition between where we
+	// check whether res.infoHash exists in the ms.incomingInfoHashes, and where we add the infoHash
+	// to the incomingInfoHashes at the end of this function.
+
 	IPs := res.PeerIP.String()
 	var rhostport string
 	if IPs == "<nil>" {
@@ -81,6 +87,8 @@ func (ms *MetadataSink) Sink(res mainline.TrawlingResult) {
 	}
 
 	go ms.awaitMetadata(res.InfoHash, Peer{Addr: raddr})
+
+	ms.incomingInfoHashes[res.InfoHash] = struct{}{}
 }
 
 func (ms *MetadataSink) Drain() <-chan Metadata {
@@ -99,5 +107,10 @@ func (ms *MetadataSink) Terminate() {
 func (ms *MetadataSink) flush(result Metadata) {
 	if !ms.terminated {
 		ms.drain <- result
+		// Delete the infoHash from ms.incomingInfoHashes ONLY AFTER once we've flushed the
+		// metadata!
+		var infoHash [20]byte
+		copy(infoHash[:], result.InfoHash)
+		delete(ms.incomingInfoHashes, infoHash)
 	}
 }