diff --git a/scripts/install b/scripts/install
index adc65ea..32f2498 100644
--- a/scripts/install
+++ b/scripts/install
@@ -94,7 +94,9 @@ ynh_setup_source "$final_path"
 #=================================================
 
 virtualenv --system-site-packages "$final_path"
-bash -c "source $final_path/bin/activate && pip install -U setuptools && pip install --requirement $final_path/requirements-ynh.txt"
+set +u; source $final_path/bin/activate; set -u
+pip install -U setuptools
+pip install --requirement $final_path/requirements-ynh.txt
 
 #=================================================
 # CONFIGURE SEARX
diff --git a/scripts/upgrade b/scripts/upgrade
index eaff8cc..b71f771 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -104,7 +104,9 @@ ynh_system_user_create $app
 
 rm -r $final_path/lib/python2.7/site-packages/setuptools $final_path/lib/python2.7/site-packages/setuptools-*
 virtualenv --system-site-packages "$final_path"
-bash -c "source $final_path/bin/activate && pip install -U setuptools && pip install --requirement $final_path/requirements-ynh.txt --upgrade"
+set +u; source $final_path/bin/activate; set -u
+pip install -U setuptools
+pip install --requirement $final_path/requirements-ynh.txt --upgrade
 
 #=================================================
 # CONFIGURE SEARX