diff --git a/gunicorn/config.py b/gunicorn/config.py
index 64c12d0777..7bdd508aef 100644
--- a/gunicorn/config.py
+++ b/gunicorn/config.py
@@ -190,6 +190,11 @@ def env(self):
 
         return env
 
+    @property
+    def sendfile(self):
+        return self.settings['sendfile'].get() is not False
+
+
 
 class SettingMeta(type):
     def __new__(cls, name, bases, attrs):
@@ -281,6 +286,9 @@ def __lt__(self, other):
 
 
 def validate_bool(val):
+    if val is None:
+        return
+
     if isinstance(val, bool):
         return val
     if not isinstance(val, six.string_types):
diff --git a/gunicorn/http/wsgi.py b/gunicorn/http/wsgi.py
index c537166ea7..f76d722d3f 100644
--- a/gunicorn/http/wsgi.py
+++ b/gunicorn/http/wsgi.py
@@ -347,7 +347,7 @@ def write(self, arg):
         util.write(self.sock, arg, self.chunked)
 
     def can_sendfile(self):
-        return self.cfg.sendfile is not False and sendfile is not None
+        return self.cfg.sendfile and sendfile is not None
 
     def sendfile(self, respiter):
         if self.cfg.is_ssl or not self.can_sendfile():