diff --git a/resources/machines/ultimaker2.json b/resources/machines/ultimaker2.json
index d25368ac4a..e19aec1336 100644
--- a/resources/machines/ultimaker2.json
+++ b/resources/machines/ultimaker2.json
@@ -11,8 +11,8 @@
 
     "inherits": "ultimaker.json",
 
-    "machine_extruder_trains": [
-        {
+    "machine_extruder_trains": {
+        "0": {
             "machine_nozzle_heat_up_speed": {
                 "default": 2.0
             },
@@ -32,7 +32,7 @@
                 "default": 16
             }
         }
-    ],
+    },
     "machine_settings": {
         "machine_start_gcode" : { "default": "" },
         "machine_end_gcode" : { "default": "" },