diff --git a/tests/cpp/collective/test_allgather.cc b/tests/cpp/collective/test_allgather.cc
index bdfadc0c7..decad8786 100644
--- a/tests/cpp/collective/test_allgather.cc
+++ b/tests/cpp/collective/test_allgather.cc
@@ -47,7 +47,7 @@ class Worker : public WorkerForTest {
 
       std::size_t n = 8192;  // n_bytes = 8192 * sizeof(int)
       std::vector<std::int32_t> data(comm_.World() * n, 0);
-      auto s_data = common::Span{data.data(), data.size()};
+      auto s_data = common::Span<std::int32_t>{data};
       auto seg = s_data.subspan(comm_.Rank() * n, n);
       std::iota(seg.begin(), seg.end(), comm_.Rank());
 
diff --git a/tests/cpp/collective/test_worker.h b/tests/cpp/collective/test_worker.h
index ad3213e81..490cdf13c 100644
--- a/tests/cpp/collective/test_worker.h
+++ b/tests/cpp/collective/test_worker.h
@@ -92,11 +92,12 @@ class TrackerTest : public SocketTest {
 
 template <typename WorkerFn>
 void TestDistributed(std::int32_t n_workers, WorkerFn worker_fn) {
-  std::chrono::seconds timeout{1};
+  std::chrono::seconds timeout{2};
 
   std::string host;
   auto rc = GetHostAddress(&host);
   ASSERT_TRUE(rc.OK()) << rc.Report();
+  LOG(INFO) << "Using " << n_workers << " workers for test.";
   RabitTracker tracker{StringView{host}, n_workers, 0, timeout};
   auto fut = tracker.Run();