diff --git a/cpp/bench/ann/src/raft/raft_ivf_flat_wrapper.h b/cpp/bench/ann/src/raft/raft_ivf_flat_wrapper.h
index cf04e07d19..bdd688f29b 100644
--- a/cpp/bench/ann/src/raft/raft_ivf_flat_wrapper.h
+++ b/cpp/bench/ann/src/raft/raft_ivf_flat_wrapper.h
@@ -96,7 +96,8 @@ RaftIvfFlatGpu<T, IdxT>::RaftIvfFlatGpu(Metric metric, int dim, const BuildParam
     dimension_(dim),
     mr_(rmm::mr::get_current_device_resource(), 1024 * 1024 * 1024ull)
 {
-  index_params_.metric = parse_metric_type(metric);
+  index_params_.metric                         = parse_metric_type(metric);
+  index_params_.conservative_memory_allocation = true;
   rmm::mr::set_current_device_resource(&mr_);
   RAFT_CUDA_TRY(cudaGetDevice(&device_));
 }