diff --git a/idb/postgres/postgres.go b/idb/postgres/postgres.go
index 0b8ff2e7..d1e88158 100644
--- a/idb/postgres/postgres.go
+++ b/idb/postgres/postgres.go
@@ -575,13 +575,15 @@ func buildTransactionQuery(tf idb.TransactionFilter) (query string, whereArgs []
 	}
 	if !tf.BeforeTime.IsZero() {
 		convertedTime := tf.BeforeTime.In(time.UTC)
-		whereParts = append(whereParts, fmt.Sprintf("h.realtime < $%d", partNumber))
+		whereParts = append(whereParts, fmt.Sprintf("t.round <= ("+
+			"SELECT round from block_header WHERE realtime < $%d ORDER BY realtime DESC LIMIT 1)", partNumber))
 		whereArgs = append(whereArgs, convertedTime)
 		partNumber++
 	}
 	if !tf.AfterTime.IsZero() {
 		convertedTime := tf.AfterTime.In(time.UTC)
-		whereParts = append(whereParts, fmt.Sprintf("h.realtime > $%d", partNumber))
+		whereParts = append(whereParts, fmt.Sprintf("t.round >= ("+
+			"SELECT round from block_header WHERE realtime > $%d ORDER BY realtime ASC LIMIT 1)", partNumber))
 		whereArgs = append(whereArgs, convertedTime)
 		partNumber++
 	}