diff --git a/poloniex/__init__.py b/poloniex/__init__.py
index 6af9a7c6..408310de 100644
--- a/poloniex/__init__.py
+++ b/poloniex/__init__.py
@@ -719,7 +719,7 @@ def on_open(self, *ws):
             if 'sub' in self.channels[chan] and self.channels[chan]['sub']:
                 self.subscribe(chan)
 
-    def on_message(self, data):
+    def on_message(self, app, data):
         if not self.jsonNums:
             message = _loads(data, parse_float=str)
         else: