diff --git a/cpp/bench/ann/src/cuvs/cuvs_cagra_wrapper.h b/cpp/bench/ann/src/cuvs/cuvs_cagra_wrapper.h
index f5f609710..e611ea36b 100644
--- a/cpp/bench/ann/src/cuvs/cuvs_cagra_wrapper.h
+++ b/cpp/bench/ann/src/cuvs/cuvs_cagra_wrapper.h
@@ -250,13 +250,17 @@ void cuvs_cagra<T, IdxT>::set_search_param(const search_param_base& param,
     RAFT_LOG_DEBUG("moving graph to new memory space: %s", allocator_to_string(graph_mem_).c_str());
     // We create a new graph and copy to it from existing graph
     auto mr = get_mr(graph_mem_);
-    *graph_ = raft::make_device_mdarray<IdxT, int64_t>(
-      handle_, mr, raft::make_extents<int64_t>(index_->graph().extent(0), index_->graph_degree()));
 
-    raft::copy(graph_->data_handle(),
-               index_->graph().data_handle(),
-               index_->graph().size(),
+    // Create a new graph, then copy, and __only then__ replace the shared pointer.
+    auto old_graph =
+      index_->graph();  // view of graph_ if it exists, of an internal index member otherwise
+    auto new_graph = raft::make_device_mdarray<IdxT, int64_t>(handle_, mr, old_graph.extents());
+    raft::copy(new_graph.data_handle(),
+               old_graph.data_handle(),
+               old_graph.size(),
                raft::resource::get_cuda_stream(handle_));
+    raft::resource::sync_stream(handle_);
+    *graph_ = std::move(new_graph);
 
     // NB: update_graph() only stores a view in the index. We need to keep the graph object alive.
     index_->update_graph(handle_, make_const_mdspan(graph_->view()));