diff --git a/tests/test_governor.py b/tests/test_governor.py
index 3d939670..f819fbac 100644
--- a/tests/test_governor.py
+++ b/tests/test_governor.py
@@ -1,14 +1,15 @@
 import os
 import psycopg2
-import unittest
 import requests
+import subprocess
 import sys
 import time
+import unittest
 import yaml
 
 from governor import Governor, main, sigchld_handler, sigterm_handler
 from test_ha import true, false
-from test_postgresql import Postgresql, os_system, psycopg2_connect
+from test_postgresql import Postgresql, subprocess_call, psycopg2_connect
 from test_etcd import requests_get, requests_put, requests_delete
 
 if sys.hexversion >= 0x03000000:
@@ -38,7 +39,7 @@ class TestGovernor(unittest.TestCase):
 
     def set_up(self):
         self.touched = False
-        os.system = os_system
+        subprocess.call = subprocess_call
         psycopg2.connect = psycopg2_connect
         requests.get = requests_get
         requests.put = requests_put
diff --git a/tests/test_postgresql.py b/tests/test_postgresql.py
index 473b9243..14ad04d4 100644
--- a/tests/test_postgresql.py
+++ b/tests/test_postgresql.py
@@ -3,8 +3,9 @@
 
 import os
 import psycopg2
-import unittest
 import shutil
+import subprocess
+import unittest
 
 from helpers.etcd import Cluster, Member
 from helpers.postgresql import Postgresql
@@ -14,7 +15,7 @@ def nop(*args, **kwargs):
     pass
 
 
-def os_system(cmd):
+def subprocess_call(cmd, shell=False):
     return 0
 
 
@@ -107,7 +108,7 @@ class TestPostgresql(unittest.TestCase):
         super(TestPostgresql, self).__init__(method_name)
 
     def set_up(self):
-        os.system = os_system
+        subprocess.call = subprocess_call
         shutil.copy = nop
         self.p = Postgresql({
             'name': 'test0',