diff --git a/badger/helpers.go b/badger/helpers.go
index 8ab5a9e..dc70ddb 100644
--- a/badger/helpers.go
+++ b/badger/helpers.go
@@ -92,7 +92,8 @@ func getIndexKeysForEvent(evt *nostr.Event, idx []byte) [][]byte {
 			// not indexable
 			continue
 		}
-		if i > 0 && evt.Tags[i-1][1] == tag[1] {
+		firstIndex := slices.IndexFunc(evt.Tags, func(t nostr.Tag) bool { return len(t) >= 2 && t[1] == tag[1] })
+		if firstIndex != i {
 			// duplicate
 			continue
 		}
diff --git a/lmdb/helpers.go b/lmdb/helpers.go
index fbe179f..fef9dbb 100644
--- a/lmdb/helpers.go
+++ b/lmdb/helpers.go
@@ -85,7 +85,8 @@ func (b *LMDBBackend) getIndexKeysForEvent(evt *nostr.Event) []key {
 			// not indexable
 			continue
 		}
-		if i > 0 && evt.Tags[i-1][1] == tag[1] {
+		firstIndex := slices.IndexFunc(evt.Tags, func(t nostr.Tag) bool { return len(t) >= 2 && t[1] == tag[1] })
+		if firstIndex != i {
 			// duplicate
 			continue
 		}