diff --git a/plugins/CuraEngineBackend/StartSliceJob.py b/plugins/CuraEngineBackend/StartSliceJob.py
index 63a345c13e..f3f34f4c3d 100644
--- a/plugins/CuraEngineBackend/StartSliceJob.py
+++ b/plugins/CuraEngineBackend/StartSliceJob.py
@@ -278,12 +278,12 @@ class StartSliceJob(Job):
     #   \return A dictionary of replacement tokens to the values they should be
     #   replaced with.
     def _buildReplacementTokens(self, stack) -> dict:
-        default_extruder_position = Application.getInstance().getMachineManager().defaultExtruderPosition
+        default_extruder_position = int(Application.getInstance().getMachineManager().defaultExtruderPosition)
         result = {}
         for key in stack.getAllKeys():
             setting_type = stack.getProperty(key, "type")
             value = stack.getProperty(key, "value")
-            if setting_type == "extruder" and value == "-1":
+            if setting_type == "extruder" and value == -1:
                 # replace with the default value
                 value = default_extruder_position
             result[key] = value