diff --git a/PanACoTA/utils_argparse.py b/PanACoTA/utils_argparse.py
index 99d1750da4b146c2f306deee40046d63ad704695..0306498de16e70fd47ca672a1378003949dec376 100644
--- a/PanACoTA/utils_argparse.py
+++ b/PanACoTA/utils_argparse.py
@@ -49,6 +49,7 @@ def cont_num(param):
 
 
 def thread_num(param):
+    import multiprocessing
     try:
         param = int(param)
     except Exception: