diff --git a/artiq/dashboard/waveform.py b/artiq/dashboard/waveform.py
index 5f702efeb..61aa144d8 100644
--- a/artiq/dashboard/waveform.py
+++ b/artiq/dashboard/waveform.py
@@ -1,21 +1,5 @@
-from PyQt5 import QtCore, QtWidgets, QtGui
-from PyQt5.QtCore import Qt
-
-from sipyco.asyncio_tools import atexit_register_coroutine
-from sipyco.sync_struct import Subscriber
-from sipyco.pc_rpc import AsyncioClient
-from sipyco import pyon
-
-from artiq.tools import exc_to_warning
-from artiq.gui.tools import LayoutWidget, get_open_file_name, get_save_file_name
-from artiq.gui.models import DictSyncTreeSepModel, LocalModelManager
-from artiq.gui.dndwidgets import DragDropSplitter, VDragScrollArea
-from artiq.coredevice import comm_analyzer
-from artiq.coredevice.comm_analyzer import WaveformType
-
 import os
 import numpy as np
-from operator import setitem
 import itertools
 import bisect
 import pyqtgraph as pg
@@ -24,6 +8,20 @@ import logging
 import math
 import struct
 
+from PyQt5 import QtCore, QtWidgets, QtGui
+from PyQt5.QtCore import Qt
+
+from sipyco.sync_struct import Subscriber
+from sipyco.pc_rpc import AsyncioClient
+from sipyco import pyon
+
+from artiq.tools import exc_to_warning
+from artiq.gui.tools import LayoutWidget, get_open_file_name, get_save_file_name
+from artiq.gui.models import DictSyncTreeSepModel
+from artiq.gui.dndwidgets import VDragDropSplitter, VDragScrollArea
+from artiq.coredevice import comm_analyzer
+from artiq.coredevice.comm_analyzer import WaveformType
+
 logger = logging.getLogger(__name__)
 
 DISPLAY_LOW = 0