diff --git a/supervisor/options.py b/supervisor/options.py
index e05266429..75c61b5be 100644
--- a/supervisor/options.py
+++ b/supervisor/options.py
@@ -1978,7 +1978,7 @@ def load_external_environment_definition_for_config(cls, config):
             try:
                 from subprocess import check_output, CalledProcessError
                 kwargs = dict(shell=True)
-                if not PY2:
+                if sys.version_info.major >= 3 and sys.version_info.minor >= 7:
                     kwargs['text'] = True
 
                 envdata = check_output(config.environment_loader, **kwargs)