diff --git a/plugins/USBPrinting/USBPrinterOutputDevice.py b/plugins/USBPrinting/USBPrinterOutputDevice.py

index ae442fbf4..c44280353 100644

--- a/plugins/USBPrinting/USBPrinterOutputDevice.py

+++ b/plugins/USBPrinting/USBPrinterOutputDevice.py

@@ -314,7 +314,7 @@ class USBPrinterOutputDevice(PrinterOutputDevice):

     ##  Try to connect the serial. This simply starts the thread, which runs _connect.

     @pyqtSlot()

     def _connect(self):

-        if not self._update_firmware_thread._updating_firmware and not self._connect_thread.isAlive() and self._connection_state in [ConnectionState.closed, ConnectionState.error]:

+        if not self._update_firmware_thread._updating_firmware and not self._connect_thread.is_alive() and self._connection_state in [ConnectionState.closed, ConnectionState.error]:

             self._connect_thread.start()

     ##  Upload new firmware to machine

@@ -636,11 +636,11 @@ class ConnectThread:

     def start(self):

         return  self._thread.start()

-    def isAlive(self):

-        return  self._thread.isAlive()

+    def is_alive(self):

+        return  self._thread.is_alive()

     def wrapup(self):

-        if self._thread.isAlive():

+        if self._thread.is_alive():

             try:

                 # TODO: to avoid waiting indefinitely, notify the thread that it needs

                 # to return immediatly.