diff --git a/resources/definitions/ultimaker.def.json b/resources/definitions/ultimaker.def.json
index e8eae781d1..aaa70e6385 100644
--- a/resources/definitions/ultimaker.def.json
+++ b/resources/definitions/ultimaker.def.json
@@ -47,6 +47,9 @@
         "line_width": {
             "value": "machine_nozzle_size"
         },
+        "wall_thickness": {
+            "value": "wall_line_width_0 + wall_line_width_x"
+        },
         "infill_before_walls": {
             "value": "False"
         },