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.