diff --git a/daqviewer/daqviewer.py b/daqviewer/daqviewer.py
index 1dab24d..d822a73 100644
--- a/daqviewer/daqviewer.py
+++ b/daqviewer/daqviewer.py
@@ -152,24 +152,24 @@ def parse_contents(contents, filename, date):
     return elements
 
 
-@app.callback(Output('output-data-upload', 'children'), [
+@app.callback([Output('output-data-upload', 'children')], [
     Input('upload-data', 'contents'),
     Input('upload-data', 'filename'),
-    Input('upload-data', 'last_modified')
+    Input('upload-data', 'last_modified'),
 ])
-def update_output(list_of_contents, list_of_names, list_of_dates):
-    if list_of_contents is not None:
+def update_output(contents, names, dates):
+    if contents is not None:
         children = [
-            parse_contents(c, n, d)
-            for c, n, d in zip(list_of_contents, list_of_names, list_of_dates)
+            parse_contents(c, n, d) for c, n, d in zip(contents, names, dates)
         ]
+
         return children
 
 
 def main():
     port = 8050
     wb.open('http://localhost:{}'.format(port))
-    app.run_server(port=port, debug=False)
+    app.run_server(port=port, debug=True)
 
 
 if __name__ == '__main__':