diff --git a/mcdc/main.py b/mcdc/main.py
index 69d3f837..974cc417 100644
--- a/mcdc/main.py
+++ b/mcdc/main.py
@@ -438,6 +438,7 @@ def prepare():
         scramble = iqmc["scramble"]
         N_dim = iqmc["N_dim"]
         seed = iqmc["seed"]
+        N_particle = mcdc["setting"]["N_particle"]
 
         mcdc["mpi_size"] = MPI.COMM_WORLD.Get_size()
         mcdc["mpi_rank"] = MPI.COMM_WORLD.Get_rank()