diff --git a/ptvsd/wrapper.py b/ptvsd/wrapper.py
index d346fcba..70ededf6 100644
--- a/ptvsd/wrapper.py
+++ b/ptvsd/wrapper.py
@@ -518,8 +518,8 @@ class VSCodeMessageProcessor(ipcjson.SocketIO, ipcjson.IpcChannel):
     def on_stackTrace(self, request, args):
         # TODO: docstring
         tid = int(args['threadId'])
-        startFrame = int(args['startFrame'])
-        levels = int(args['levels'])
+        startFrame = int(args.get('startFrame', 0))
+        levels = int(args.get('levels', 0))
 
         tid = self.thread_map.to_pydevd(tid)
         with self.stack_traces_lock: