diff --git a/tests/test_ifs_sim.py b/tests/test_ifs_sim.py
index e3d2c38fdcb07ea3f7e40f936f3164ec24961659..d08e0545435c3ed3d92de75b1432b4e30f509989 100644
--- a/tests/test_ifs_sim.py
+++ b/tests/test_ifs_sim.py
@@ -48,7 +48,7 @@ class TestDemoFunction(unittest.TestCase):
         debug = True
 
         # result_path = dir_path+'ifs_sim_result'
-        result_path =os.path.join(dir_path, 'ifs_sim_result')
+        result_path = os.path.join(dir_path, 'ifs_sim_result')
         
         csst_ifs_sim.runIFSsim(sourcein, configfile,
                                dir_path, result_path, 1, debug, 'no')