diff --git a/cura/PrinterOutputDevice.py b/cura/PrinterOutputDevice.py
index 236b658eba..969aa3c460 100644
--- a/cura/PrinterOutputDevice.py
+++ b/cura/PrinterOutputDevice.py
@@ -8,8 +8,6 @@ from PyQt5.QtCore import pyqtProperty, pyqtSignal, QObject, QTimer, QUrl
 from PyQt5.QtWidgets import QMessageBox
 
 from UM.Logger import Logger
-from UM.FileHandler.FileHandler import FileHandler #For typing.
-from UM.Scene.SceneNode import SceneNode #For typing.
 from UM.Signal import signalemitter
 from UM.Qt.QtApplication import QtApplication
 from UM.FlameProfiler import pyqtSlot
@@ -22,6 +20,8 @@ if MYPY:
     from cura.PrinterOutput.PrinterOutputModel import PrinterOutputModel
     from cura.PrinterOutput.ConfigurationModel import ConfigurationModel
     from cura.PrinterOutput.FirmwareUpdater import FirmwareUpdater
+    from UM.FileHandler.FileHandler import FileHandler
+    from UM.Scene.SceneNode import SceneNode
 
 i18n_catalog = i18nCatalog("cura")
 
@@ -131,7 +131,7 @@ class PrinterOutputDevice(QObject, OutputDevice):
 
         return None
 
-    def requestWrite(self, nodes: List[SceneNode], file_name: Optional[str] = None, limit_mimetypes: bool = False, file_handler: Optional[FileHandler] = None, **kwargs: str) -> None:
+    def requestWrite(self, nodes: List["SceneNode"], file_name: Optional[str] = None, limit_mimetypes: bool = False, file_handler: Optional["FileHandler"] = None, **kwargs: str) -> None:
         raise NotImplementedError("requestWrite needs to be implemented")
 
     @pyqtProperty(QObject, notify = printersChanged)
diff --git a/plugins/USBPrinting/AvrFirmwareUpdater.py b/plugins/USBPrinting/AvrFirmwareUpdater.py
index 505e1ddb7e..b8650e9208 100644
--- a/plugins/USBPrinting/AvrFirmwareUpdater.py
+++ b/plugins/USBPrinting/AvrFirmwareUpdater.py
@@ -4,7 +4,6 @@
 from UM.Logger import Logger
 
 from cura.CuraApplication import CuraApplication
-from cura.PrinterOutputDevice import PrinterOutputDevice
 from cura.PrinterOutput.FirmwareUpdater import FirmwareUpdater, FirmwareUpdateState
 
 from .avr_isp import stk500v2, intelHex
@@ -12,8 +11,13 @@ from serial import SerialException
 
 from time import sleep
 
+MYPY = False
+if MYPY:
+    from cura.PrinterOutputDevice import PrinterOutputDevice
+
+
 class AvrFirmwareUpdater(FirmwareUpdater):
-    def __init__(self, output_device: PrinterOutputDevice) -> None:
+    def __init__(self, output_device: "PrinterOutputDevice") -> None:
         super().__init__(output_device)
 
     def _updateFirmware(self) -> None:
diff --git a/plugins/USBPrinting/USBPrinterOutputDevice.py b/plugins/USBPrinting/USBPrinterOutputDevice.py
index b5ada76e6c..4c3e7ee131 100644
--- a/plugins/USBPrinting/USBPrinterOutputDevice.py
+++ b/plugins/USBPrinting/USBPrinterOutputDevice.py
@@ -4,7 +4,6 @@
 from UM.Logger import Logger
 from UM.i18n import i18nCatalog
 from UM.Qt.Duration import DurationFormat
-from UM.PluginRegistry import PluginRegistry
 
 from cura.CuraApplication import CuraApplication
 from cura.PrinterOutputDevice import PrinterOutputDevice, ConnectionState
@@ -17,13 +16,12 @@ from .AvrFirmwareUpdater import AvrFirmwareUpdater
 
 from serial import Serial, SerialException, SerialTimeoutException
 from threading import Thread, Event
-from time import time, sleep
+from time import time
 from queue import Queue
 from typing import Union, Optional, List, cast
 
 import re
 import functools  # Used for reduce
-import os
 
 catalog = i18nCatalog("cura")