diff --git a/cfg_checker/common/settings.py b/cfg_checker/common/settings.py
index 92c17a5..cca5142 100644
--- a/cfg_checker/common/settings.py
+++ b/cfg_checker/common/settings.py
@@ -1,4 +1,5 @@
 import os
+import sys
 
 from cfg_checker.common.exception import ConfigException
 
@@ -15,11 +16,17 @@
 
 
 class CheckerConfiguration(object):
+    @staticmethod
     def load_nodes_list():
-        return utils.get_nodes_list(
-            os.environ.get('CFG_ALL_NODES', None),
-            os.environ.get('SALT_NODE_LIST_FILE', None)
-        )
+        _file = os.environ.get('SALT_NODE_LIST_FILE', None)
+        if _file:
+            _v, _ = utils.get_nodes_list(
+                os.path.join(pkg_dir, _file),
+                env_sting=os.environ.get('CFG_ALL_NODES', None)
+            )
+            return _v
+        else:
+            return None
 
     def _init_values(self):
         """Load values from environment variables or put default ones
@@ -119,6 +126,16 @@
     def __init__(self):
         """Base configuration class. Only values that are common for all scripts
         """
+        # Make sure we running on Python 3
+        if sys.version_info[0] < 3 and sys.version_info[1] < 5:
+            logger_cli.error("# ERROR: Python 3.5+ is required")
+            sys.exit(1)
+        else:
+            logger_cli.debug("### Python version is {}.{}".format(
+                sys.version_info[0],
+                sys.version_info[1]
+            ))
+
         _env = os.getenv('SALT_ENV', None)
         self._init_env(_env)
         self._init_values()