diff --git a/gunicorn/arbiter.py b/gunicorn/arbiter.py
index 24ec38744..fff0b7a57 100644
--- a/gunicorn/arbiter.py
+++ b/gunicorn/arbiter.py
@@ -93,7 +93,7 @@ def setup(self, app):
             self.log = self.cfg.logger_class(app.cfg)
 
         # reopen files
-        if 'GUNICORN_FD' in os.environ:
+        if 'GUNICORN_PID' in os.environ:
             self.log.reopen_files()
 
         self.worker_class = self.cfg.worker_class