diff --git a/channels/binding/websockets.py b/channels/binding/websockets.py
index 76a442b..e458b6b 100644
--- a/channels/binding/websockets.py
+++ b/channels/binding/websockets.py
@@ -55,7 +55,7 @@ class WebsocketBinding(Binding):
         """
         Serializes model data into JSON-compatible types.
         """
-        if self.fields == ['__all__']:
+        if list(self.fields) == ['__all__']:
             fields = None
         else:
             fields = self.fields