diff --git a/csst_ifs_sim/csst_ifs_sim.py b/csst_ifs_sim/csst_ifs_sim.py
index 2207ebedfe90952066ef1b2e157c6f130331c481..770638c9238a5ecac1b03f6c04eacbc9b2897985 100644
--- a/csst_ifs_sim/csst_ifs_sim.py
+++ b/csst_ifs_sim/csst_ifs_sim.py
@@ -162,7 +162,7 @@ from support import logger as lg
 from support import cosmicrays
 from support import IFSinstrumentModel
 
-from joblib import Parallel, delayed
+#from joblib import Parallel, delayed
 
 # from astropy.table import Table
 
diff --git a/requirements.txt b/requirements.txt
index 9de4fdd16c636a9ba0531ae1807ccc57a7826ffe..910ed527c508846a0d9f211b1c060fc27d45c2cf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,3 +5,4 @@ pandas~=1.2.3
 julian~=0.14
 astropy~=5.1
 tqdm~=4.59.0
+galsim~=2.4.5