diff --git a/resources/machines/prusa_i3.json b/resources/machines/prusa_i3.json
index 0228d22c6e..dcbca32801 100644
--- a/resources/machines/prusa_i3.json
+++ b/resources/machines/prusa_i3.json
@@ -16,6 +16,7 @@
         "machine_depth": { "default": 200 },
         "machine_center_is_zero": { "default": false },
         "machine_nozzle_size": { "default": 0.4 },
+        "material_diameter": { "default": 1.75 },
         "machine_nozzle_heat_up_speed": { "default": 2.0 },
         "machine_nozzle_cool_down_speed": { "default": 2.0 },
         "machine_head_shape_min_x": { "default": 75 },
diff --git a/resources/machines/prusa_i3_xl.json b/resources/machines/prusa_i3_xl.json
index b34a879680..b66b974983 100644
--- a/resources/machines/prusa_i3_xl.json
+++ b/resources/machines/prusa_i3_xl.json
@@ -16,6 +16,7 @@
         "machine_depth": { "default": 270 },
         "machine_center_is_zero": { "default": false },
         "machine_nozzle_size": { "default": 0.4 },
+        "material_diameter": { "default": 1.75 },
         "machine_nozzle_heat_up_speed": { "default": 2.0 },
         "machine_nozzle_cool_down_speed": { "default": 2.0 },
         "machine_head_shape_min_x": { "default": 75 },