diff --git a/cpp/include/raft/spatial/knn/knn.hpp b/cpp/include/raft/spatial/knn/knn.hpp
index 5b77239dac..38106f6e0c 100644
--- a/cpp/include/raft/spatial/knn/knn.hpp
+++ b/cpp/include/raft/spatial/knn/knn.hpp
@@ -51,9 +51,9 @@ using deviceAllocator = raft::mr::device::allocator;
  * 					 form (e.g., without raising to the 1/p power).
  */
 inline void brute_force_knn(
-  raft::handle_t &handle, std::vector<float *> &input, std::vector<int> &sizes,
-  int D, float *search_items, int n, int64_t *res_I, float *res_D, int k,
-  bool rowMajorIndex = false, bool rowMajorQuery = false,
+  raft::handle_t const &handle, std::vector<float *> &input,
+  std::vector<int> &sizes, int D, float *search_items, int n, int64_t *res_I,
+  float *res_D, int k, bool rowMajorIndex = false, bool rowMajorQuery = false,
   distance::DistanceType metric = distance::DistanceType::L2Unexpanded,
   float metric_arg = 2.0f, bool expanded = false) {
   ASSERT(input.size() == sizes.size(),