diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 2a9459d..ba587c8 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -79,7 +79,7 @@ jobs:
             export OMPI_MCA_rmaps_base_oversubscribe=1
             export RDMAV_FORK_SAFE=1
 
-            mpirun -n 4 python -m mpi4py examples/log-mpi.py
+            mpirun --map-by :OVERSUBSCRIBE -n 4 python -m mpi4py examples/log-mpi.py
 
             rm summary.sqlite
             runalyzer-gather summary.sqlite mpi-log*.sqlite