diff --git a/codejail/tests/test_safe_exec.py b/codejail/tests/test_safe_exec.py
index c876213d..97e09af2 100644
--- a/codejail/tests/test_safe_exec.py
+++ b/codejail/tests/test_safe_exec.py
@@ -101,6 +101,8 @@ def test_importing_lots_of_crap(self):
         set_limit('REALTIME', 10)
         globs = {}
         self.safe_exec(textwrap.dedent("""\
+            import os
+            os.environ['OPENBLAS_NUM_THREADS'] = '1'
             from numpy import *
             a = 1723
             """), globs)