diff --git a/tests/test_nginx_conf_valid.sh b/tests/test_nginx_conf_valid.sh
index b50ce14f758d92926143a976f41b51d94a267e04..2a735552333129934012d7ad3aa8a839d0102606 100755
--- a/tests/test_nginx_conf_valid.sh
+++ b/tests/test_nginx_conf_valid.sh
@@ -3,5 +3,7 @@
 set -e
 
 if ( which nginx >/dev/null ); then
-    nginx -t
+	nginx -t
+else
+	exit 2
 fi
diff --git a/tests/test_nginx_status.py b/tests/test_nginx_status.py
index d25431115177cdb19f9f12888ee3dd2921ceeb15..61260da376d13901c0b58f23af1cbfd1089acca9 100755
--- a/tests/test_nginx_status.py
+++ b/tests/test_nginx_status.py
@@ -10,6 +10,7 @@ import sys
 
 if not os.path.exists('/etc/nginx'):
     print('Nginx dir does not exists, test skipped.')
+    sys.exit(2)
 else:
     print('Checking http://127.0.0.1:1080/nginx_status response.')
     try:
diff --git a/tests/test_nginx_vhosts.py b/tests/test_nginx_vhosts.py
index 46009f46ecd7c2232b0cb2591f854094d09613df..f9dc59cbece36f56d30f5890593c84242224c2d3 100755
--- a/tests/test_nginx_vhosts.py
+++ b/tests/test_nginx_vhosts.py
@@ -20,7 +20,7 @@ This script checks for all enabled vhosts in Nginx conf that:
 nginx_dir = '/etc/nginx/sites-enabled'
 if not os.path.exists(nginx_dir):
     print('Nginx dir does not exists ("%s").' % nginx_dir)
-    sys.exit(0)
+    sys.exit(2)
 
 # check that Wowza is installed
 wowza_dir = '/usr/local/WowzaStreamingEngine'
diff --git a/tests/test_ntp.py b/tests/test_ntp.py
index 393a582c13df3369bf075ea0a194d376a7cbce32..eb4a957e208e978bf2031a8af57a29cba8e2adf1 100755
--- a/tests/test_ntp.py
+++ b/tests/test_ntp.py
@@ -2,7 +2,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2017, Florent Thiery
 '''
-Check that the server is synchronized with the configured NTP server.
+Checks that the server is synchronized with the configured NTP server.
 '''
 import os
 import sys
diff --git a/tests/test_postfix.py b/tests/test_postfix.py
index 7cdebf28de82c856ea9bcdf9c3a9030812ca2cba..0e343931e35db4fdebbf7560b528386528780b5b 100755
--- a/tests/test_postfix.py
+++ b/tests/test_postfix.py
@@ -9,7 +9,7 @@ import sys
 
 
 if not os.path.exists('/etc/postfix'):
-    print('Postfix dir does not exists, test skipped.')
+    print('Postfix dir does not exists, please install postfix.')
     sys.exit(1)
 else:
     # check that postfix listens the port 25 correctly