diff --git a/pcigale/__init__.py b/pcigale/__init__.py
index 525fc053f62f1f25ebc76333914de34dc9ab9885..161005ea66907edcb1f6281a54a0c1a94bdda007 100644
--- a/pcigale/__init__.py
+++ b/pcigale/__init__.py
@@ -3,6 +3,15 @@
 # Licensed under the CeCILL-v2 licence - see Licence_CeCILL_V2-en.txt
 # Author: Yannick Roehlly
 
+import os
+# Set environment variables to disable multithreading as users will probably
+# want to set the number of cores to the max of their computer.
+os.environ["OMP_NUM_THREADS"] = "1"
+os.environ["OPENBLAS_NUM_THREADS"] = "1"
+os.environ["MKL_NUM_THREADS"] = "1"
+os.environ["VECLIB_MAXIMUM_THREADS"] = "1"
+os.environ["NUMEXPR_NUM_THREADS"] = "1"
+
 import argparse
 import multiprocessing as mp
 import sys
diff --git a/pcigale_plots/__init__.py b/pcigale_plots/__init__.py
index d17eff7d8682df278a7bd724864c103f192515ce..822d918b5b8540cb0825d4299d951bb860ffab29 100644
--- a/pcigale_plots/__init__.py
+++ b/pcigale_plots/__init__.py
@@ -6,6 +6,15 @@
 # Licensed under the CeCILL-v2 licence - see Licence_CeCILL_V2-en.txt
 # Author: Yannick Roehlly, Médéric Boquien & Denis Burgarella
 
+import os
+# Set environment variables to disable multithreading as users will probably
+# want to set the number of cores to the max of their computer.
+os.environ["OMP_NUM_THREADS"] = "1"
+os.environ["OPENBLAS_NUM_THREADS"] = "1"
+os.environ["MKL_NUM_THREADS"] = "1"
+os.environ["VECLIB_MAXIMUM_THREADS"] = "1"
+os.environ["NUMEXPR_NUM_THREADS"] = "1"
+
 import argparse
 import sys
 from os import path