diff --git a/score.go b/score.go
index e88f45a..6c56e88 100644
--- a/score.go
+++ b/score.go
@@ -125,7 +125,7 @@ type peerScore struct {
 	peerStats map[peer.ID]*peerStats
 
 	// IP colocation tracking
-	peerIPs map[string]peer.ID
+	peerIPs map[string]map[peer.ID]struct{}
 }
 
 func newPeerScore(params *PeerScoreParams) *peerScore {