diff --git a/gunicorn/config.py b/gunicorn/config.py
index 1901d492..35d7ae22 100644
--- a/gunicorn/config.py
+++ b/gunicorn/config.py
@@ -319,7 +319,12 @@ class Bind(Setting):
     cli = ["-b", "--bind"]
     meta = "ADDRESS"
     validator = validate_string
-    default = "127.0.0.1:8000"
+
+    if 'PORT' in os.environ:
+        default = '0.0.0.0:{0}'.format(os.environ.get('PORT'))
+    else:
+        default = '127.0.0.1:8000'
+
     desc = """\
         The socket to bind.