diff --git a/resources/definitions/fdmprinter.def.json b/resources/definitions/fdmprinter.def.json
index f067195b42..7de75d03f0 100644
--- a/resources/definitions/fdmprinter.def.json
+++ b/resources/definitions/fdmprinter.def.json
@@ -4785,7 +4785,7 @@
                     "unit": "mm",
                     "type": "float",
                     "default_value": 0.0,
-                    "value": "(z_seam_x if machine_center_is_zero else z_seam_x + machine_width / 2) if (layer_start_at_z_seam and z_seam_type == 'back') else (sum(extruderValues('machine_extruder_start_pos_x')) / len(extruderValues('machine_extruder_start_pos_x')))",
+                    "value": "(z_seam_x + machine_width / 2 if (not machine_center_is_zero and z_seam_relative) else z_seam_x) if (layer_start_at_z_seam and z_seam_type == 'back') else (sum(extruderValues('machine_extruder_start_pos_x')) / len(extruderValues('machine_extruder_start_pos_x')))",
                     "minimum_value": "machine_width / -2 if machine_center_is_zero else 0",
                     "settable_per_mesh": false,
                     "settable_per_extruder": true,
@@ -4798,7 +4798,7 @@
                     "unit": "mm",
                     "type": "float",
                     "default_value": 0.0,
-                    "value": "(z_seam_y if machine_center_is_zero else z_seam_y + machine_depth / 2) if (layer_start_at_z_seam and z_seam_type == 'back') else (sum(extruderValues('machine_extruder_start_pos_y')) / len(extruderValues('machine_extruder_start_pos_y')))",
+                    "value": "(z_seam_y + machine_depth / 2 if (not machine_center_is_zero and z_seam_relative) else z_seam_y) if (layer_start_at_z_seam and z_seam_type == 'back') else (sum(extruderValues('machine_extruder_start_pos_y')) / len(extruderValues('machine_extruder_start_pos_y')))",
                     "minimum_value": "machine_depth / -2 if machine_center_is_zero else 0",
                     "settable_per_mesh": false,
                     "settable_per_extruder": true,