diff --git a/cpp/include/raft/spatial/knn/detail/ann_quantized_faiss.cuh b/cpp/include/raft/spatial/knn/detail/ann_quantized_faiss.cuh
index bb37fd03db..6e4c99b646 100644
--- a/cpp/include/raft/spatial/knn/detail/ann_quantized_faiss.cuh
+++ b/cpp/include/raft/spatial/knn/detail/ann_quantized_faiss.cuh
@@ -18,6 +18,9 @@
 
 #include "../ann_common.h"
 
+#include "common_faiss.h"
+#include "processing.hpp"
+
 #include <raft/cudart_utils.h>
 #include <raft/cuda_utils.cuh>
 
diff --git a/cpp/include/raft/spatial/knn/detail/common_faiss.h b/cpp/include/raft/spatial/knn/detail/common_faiss.h
new file mode 100644
index 0000000000..0c0398a336
--- /dev/null
+++ b/cpp/include/raft/spatial/knn/detail/common_faiss.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2020-2021, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <raft/cudart_utils.h>
+#include <raft/cuda_utils.cuh>
+
+#include <faiss/gpu/GpuDistance.h>
+#include <raft/linalg/distance_type.h>
+
+namespace raft {
+namespace spatial {
+namespace knn {
+namespace detail {
+
+inline faiss::MetricType build_faiss_metric(
+  raft::distance::DistanceType metric) {
+  switch (metric) {
+    case raft::distance::DistanceType::CosineExpanded:
+      return faiss::MetricType::METRIC_INNER_PRODUCT;
+    case raft::distance::DistanceType::CorrelationExpanded:
+      return faiss::MetricType::METRIC_INNER_PRODUCT;
+    case raft::distance::DistanceType::L2Expanded:
+      return faiss::MetricType::METRIC_L2;
+    case raft::distance::DistanceType::L2Unexpanded:
+      return faiss::MetricType::METRIC_L2;
+    case raft::distance::DistanceType::L2SqrtExpanded:
+      return faiss::MetricType::METRIC_L2;
+    case raft::distance::DistanceType::L2SqrtUnexpanded:
+      return faiss::MetricType::METRIC_L2;
+    case raft::distance::DistanceType::L1:
+      return faiss::MetricType::METRIC_L1;
+    case raft::distance::DistanceType::InnerProduct:
+      return faiss::MetricType::METRIC_INNER_PRODUCT;
+    case raft::distance::DistanceType::LpUnexpanded:
+      return faiss::MetricType::METRIC_Lp;
+    case raft::distance::DistanceType::Linf:
+      return faiss::MetricType::METRIC_Linf;
+    case raft::distance::DistanceType::Canberra:
+      return faiss::MetricType::METRIC_Canberra;
+    case raft::distance::DistanceType::BrayCurtis:
+      return faiss::MetricType::METRIC_BrayCurtis;
+    case raft::distance::DistanceType::JensenShannon:
+      return faiss::MetricType::METRIC_JensenShannon;
+    default:
+      THROW("MetricType not supported: %d", metric);
+  }
+}
+
+}  // namespace detail
+}  // namespace knn
+}  // namespace spatial
+}  // namespace raft
diff --git a/cpp/include/raft/spatial/knn/detail/knn_brute_force_faiss.cuh b/cpp/include/raft/spatial/knn/detail/knn_brute_force_faiss.cuh
index 75226299e6..09494e9eb1 100644
--- a/cpp/include/raft/spatial/knn/detail/knn_brute_force_faiss.cuh
+++ b/cpp/include/raft/spatial/knn/detail/knn_brute_force_faiss.cuh
@@ -36,6 +36,8 @@
 #include "haversine_distance.cuh"
 #include "processing.hpp"
 
+#include "common_faiss.h"
+
 namespace raft {
 namespace spatial {
 namespace knn {
@@ -167,40 +169,6 @@ inline void knn_merge_parts(value_t *inK, value_idx *inV, value_t *outK,
       inK, inV, outK, outV, n_samples, n_parts, k, stream, translations);
 }
 
-inline faiss::MetricType build_faiss_metric(
-  raft::distance::DistanceType metric) {
-  switch (metric) {
-    case raft::distance::DistanceType::CosineExpanded:
-      return faiss::MetricType::METRIC_INNER_PRODUCT;
-    case raft::distance::DistanceType::CorrelationExpanded:
-      return faiss::MetricType::METRIC_INNER_PRODUCT;
-    case raft::distance::DistanceType::L2Expanded:
-      return faiss::MetricType::METRIC_L2;
-    case raft::distance::DistanceType::L2Unexpanded:
-      return faiss::MetricType::METRIC_L2;
-    case raft::distance::DistanceType::L2SqrtExpanded:
-      return faiss::MetricType::METRIC_L2;
-    case raft::distance::DistanceType::L2SqrtUnexpanded:
-      return faiss::MetricType::METRIC_L2;
-    case raft::distance::DistanceType::L1:
-      return faiss::MetricType::METRIC_L1;
-    case raft::distance::DistanceType::InnerProduct:
-      return faiss::MetricType::METRIC_INNER_PRODUCT;
-    case raft::distance::DistanceType::LpUnexpanded:
-      return faiss::MetricType::METRIC_Lp;
-    case raft::distance::DistanceType::Linf:
-      return faiss::MetricType::METRIC_Linf;
-    case raft::distance::DistanceType::Canberra:
-      return faiss::MetricType::METRIC_Canberra;
-    case raft::distance::DistanceType::BrayCurtis:
-      return faiss::MetricType::METRIC_BrayCurtis;
-    case raft::distance::DistanceType::JensenShannon:
-      return faiss::MetricType::METRIC_JensenShannon;
-    default:
-      THROW("MetricType not supported: %d", metric);
-  }
-}
-
 /**
  * Search the kNN for the k-nearest neighbors of a set of query vectors
  * @param[in] input vector of device device memory array pointers to search