diff --git a/sohstationviewer/view/channel_prefer_dialog.py b/sohstationviewer/view/channel_prefer_dialog.py
index bdbe3d24bcafa8561e0599acd9ae316d086aee4f..9775b9bf90e967612fae4ba292d0606129d55249 100755
--- a/sohstationviewer/view/channel_prefer_dialog.py
+++ b/sohstationviewer/view/channel_prefer_dialog.py
@@ -464,7 +464,8 @@ class ChannelPreferDialog(OneWindowAtATimeDialog):
                 if widget is not None:
                     widget.setParent(None)
             self.channel_info = read_mseed_channels(
-                self.tracking_info_text_browser, self.list_of_dir, is_multiplex)
+                self.tracking_info_text_browser,
+                self.list_of_dir, is_multiplex)
             if len(self.channel_info) == 0:
                 msg = "No data can be read from " + ', '.join(self.list_of_dir)
                 return QtWidgets.QMessageBox.warning(self, "No data", msg)