diff --git a/plugins/USBPrinting/USBPrinterOutputDevice.py b/plugins/USBPrinting/USBPrinterOutputDevice.py
index 580bbf06df..2ca7e4ecc7 100644
--- a/plugins/USBPrinting/USBPrinterOutputDevice.py
+++ b/plugins/USBPrinting/USBPrinterOutputDevice.py
@@ -563,19 +563,19 @@ class USBPrinterOutputDevice(PrinterOutputDevice):
             line = line[:line.find(";")]
         line = line.strip()
 
-        # Don't send empty lines. But we do have to send something, so send m105 instead.
-        if line == "":
+        # Don't send empty lines. But we do have to send something, so send
+        # m105 instead.
+        # Don't send the M0 or M1 to the machine, as M0 and M1 are handled as
+        # an LCD menu pause.
+        if line == "" or line == "M1" or line == "M1":
             line = "M105"
-
         try:
-            if line == "M0" or line == "M1":
-                line = "M105"  # Don't send the M0 or M1 to the machine, as M0 and M1 are handled as an LCD menu pause.
             if ("G0" in line or "G1" in line) and "Z" in line:
                 z = float(re.search("Z([0-9\.]*)", line).group(1))
                 if self._current_z != z:
                     self._current_z = z
         except Exception as e:
-            Logger.log("e", "Unexpected error with printer connection: %s" % e)
+            Logger.log("e", "Unexpected error with printer connection, could not parse current Z: %s: %s" % (e, line))
             self._setErrorState("Unexpected error: %s" %e)
         checksum = functools.reduce(lambda x,y: x^y, map(ord, "N%d%s" % (self._gcode_position, line)))
 
@@ -674,4 +674,4 @@ class USBPrinterOutputDevice(PrinterOutputDevice):
     def cancelPreheatBed(self):
         Logger.log("i", "Cancelling pre-heating of the bed.")
         self._setTargetBedTemperature(0)
-        self.preheatBedRemainingTimeChanged.emit()
\ No newline at end of file
+        self.preheatBedRemainingTimeChanged.emit()