diff --git a/plugins/PostProcessingPlugin/scripts/ChangeAtZ.py b/plugins/PostProcessingPlugin/scripts/ChangeAtZ.py
index e152bdf627..ba7b06bb1b 100644
--- a/plugins/PostProcessingPlugin/scripts/ChangeAtZ.py
+++ b/plugins/PostProcessingPlugin/scripts/ChangeAtZ.py
@@ -330,7 +330,7 @@ class ChangeAtZ(Script):
             "extruderOne": self.getSettingValueByKey("i2_extruderOne"),
             "extruderTwo": self.getSettingValueByKey("i4_extruderTwo"),
             "fanSpeed": self.getSettingValueByKey("j2_fanSpeed")}
-        old = {"speed": -1, "flowrate": -1, "flowrateOne": -1, "flowrateTwo": -1, "platformTemp": -1, "extruderOne": -1,
+        old = {"speed": -1, "flowrate": 100, "flowrateOne": -1, "flowrateTwo": -1, "platformTemp": -1, "extruderOne": -1,
             "extruderTwo": -1, "bedTemp": -1, "fanSpeed": -1, "state": -1}
         twLayers = self.getSettingValueByKey("d_twLayers")
         if self.getSettingValueByKey("c_behavior") == "single_layer":
@@ -410,6 +410,8 @@ class ChangeAtZ(Script):
                     tmp_extruder = self.getValue(line, "T", None)
                     if tmp_extruder == None: #check if extruder is specified
                         old["flowrate"] = self.getValue(line, "S", old["flowrate"])
+                        if old["flowrate"] == -1:
+                            old["flowrate"] = 100.0
                     elif tmp_extruder == 0: #first extruder
                         old["flowrateOne"] = self.getValue(line, "S", old["flowrateOne"])
                     elif tmp_extruder == 1: #second extruder
@@ -481,9 +483,9 @@ class ChangeAtZ(Script):
                             state = 2
                             done_layers = 0
                             if targetL_i > -100000:
-                                modified_gcode += ";ChangeAtZ V%s: reset below Layer %d\n" % (self.version,targetL_i)
+                                modified_gcode += ";ChangeAtZ V%s: reset below Layer %d\n" % (self.version, targetL_i)
                             else:
-                                modified_gcode += ";ChangeAtZ V%s: reset below %1.2f mm\n" % (self.version,targetZ)
+                                modified_gcode += ";ChangeAtZ V%s: reset below %1.2f mm\n" % (self.version, targetZ)
                             if IsUM2 and oldValueUnknown: #executes on UM2 with Ultigcode and machine setting
                                 modified_gcode += "M606 S%d;recalls saved settings\n" % (TWinstances-1)
                             else: #executes on RepRap, UM2 with Ultigcode and Cura setting