diff --git a/cpp/include/cuml/neighbors/knn.hpp b/cpp/include/cuml/neighbors/knn.hpp
index d91a7d035e..5eb208b1ed 100644
--- a/cpp/include/cuml/neighbors/knn.hpp
+++ b/cpp/include/cuml/neighbors/knn.hpp
@@ -46,6 +46,10 @@ struct knnIndex {
   ~knnIndex() {
     delete index;
     delete gpu_res;
+
+    // to check that destructor is not called twice
+    index = nullptr;
+    gpu_res = nullptr;
   }
 };
 
diff --git a/cpp/src_prims/selection/knn.cuh b/cpp/src_prims/selection/knn.cuh
index 4d3a0f5dc7..8d91a03cf7 100644
--- a/cpp/src_prims/selection/knn.cuh
+++ b/cpp/src_prims/selection/knn.cuh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2020, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2021, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -270,7 +270,8 @@ void approx_knn_build_index(ML::knnIndex *index, ML::knnIndexParam *params,
 
   faiss::gpu::StandardGpuResources *gpu_res =
     new faiss::gpu::StandardGpuResources();
-  gpu_res->noTempMemory();
+  //gpu_res->noTempMemory();
+  gpu_res->setTempMemory(3000000000);
   gpu_res->setCudaMallocWarning(false);
   gpu_res->setDefaultStream(device, userStream);
   index->gpu_res = gpu_res;