diff --git a/modules/flann/include/opencv2/flann/lsh_index.h b/modules/flann/include/opencv2/flann/lsh_index.h
index f3e0642199..a050c3ca2b 100644
--- a/modules/flann/include/opencv2/flann/lsh_index.h
+++ b/modules/flann/include/opencv2/flann/lsh_index.h
@@ -197,6 +197,8 @@ public:
         KNNUniqueResultSet<DistanceType> resultSet(knn);
         for (size_t i = 0; i < queries.rows; i++) {
             resultSet.clear();
+            std::fill_n(indices[i], knn, -1);
+            std::fill_n(dists[i], knn, std::numeric_limits<DistanceType>::max());
             findNeighbors(resultSet, queries[i], params);
             if (get_param(params,"sorted",true)) resultSet.sortAndCopy(indices[i], dists[i], knn);
             else resultSet.copy(indices[i], dists[i], knn);