diff --git a/notebooks/mpi_collectives.ipynb b/notebooks/mpi_collectives.ipynb
index c0785d1..1cdfd6b 100644
--- a/notebooks/mpi_collectives.ipynb
+++ b/notebooks/mpi_collectives.ipynb
@@ -771,9 +771,11 @@
     "    rank = MPI.Comm_rank(comm)\n",
     "    if rank == 2\n",
     "        sndbuf = [2]\n",
-    "        MPI.Send(sndbuf, comm2; dest=3, tag=0)\n",
+    "        req1 = MPI.Isend(sndbuf, comm2; dest=3, tag=0)\n",
     "        sndbuf = [1]\n",
-    "        MPI.Send(sndbuf, comm; dest=3, tag=0)\n",
+    "        req2 = MPI.Isend(sndbuf, comm; dest=3, tag=0)\n",
+    "        MPI.Wait(req2)\n",
+    "        MPI.Wait(req1)\n",
     "    end\n",
     "    if rank == 3\n",
     "        rcvbuf = zeros(Int,1)\n",