diff --git a/storage/memorybysubnet/peer_store.go b/storage/memorybysubnet/peer_store.go
index 417536e..d5f1b47 100644
--- a/storage/memorybysubnet/peer_store.go
+++ b/storage/memorybysubnet/peer_store.go
@@ -547,6 +547,9 @@ func (s *peerStore) collectGarbage(cutoff time.Time) error {
 						delete(shard.swarms[ih].leechers[subnet], pk)
 					}
 				}
+				if len(shard.swarms[ih].leechers[subnet]) == 0 {
+					delete(shard.swarms[ih].leechers, subnet)
+				}
 			}
 
 			for subnet := range shard.swarms[ih].seeders {
@@ -555,6 +558,9 @@ func (s *peerStore) collectGarbage(cutoff time.Time) error {
 						delete(shard.swarms[ih].seeders[subnet], pk)
 					}
 				}
+				if len(shard.swarms[ih].seeders[subnet]) == 0 {
+					delete(shard.swarms[ih].seeders, subnet)
+				}
 			}
 
 			// TODO(jzelinskie): fix this to sum all peers in all subnets