diff --git a/resources/machines/ultimaker2.json b/resources/machines/ultimaker2.json
index 7825650bdc..fb9e980b86 100644
--- a/resources/machines/ultimaker2.json
+++ b/resources/machines/ultimaker2.json
@@ -11,8 +11,8 @@
     "inherits": "fdmprinter.json",
 
     
-    "machine_extruder_trains": [
-        {
+    "machine_extruder_trains": {
+        "0": {
             "machine_nozzle_size": {
                 "default": 0.4
             },
@@ -35,7 +35,7 @@
                 "default": 16
             }
         }
-    ],
+    },
     "overrides": {
         "machine_start_gcode" : { "default": "" },
         "machine_end_gcode" : { "default": "" },
diff --git a/resources/machines/ultimaker_original.json b/resources/machines/ultimaker_original.json
index 14ff6c312b..1ec13c0005 100644
--- a/resources/machines/ultimaker_original.json
+++ b/resources/machines/ultimaker_original.json
@@ -16,8 +16,8 @@
         "BedLeveling"
     ],
 
-    "machine_extruder_trains": [
-        {
+    "machine_extruder_trains": {
+        "0": {
             "machine_nozzle_size": {
                 "default": 0.4
             },
@@ -40,7 +40,7 @@
                 "default": 16
             }
         }
-    ],
+    },
     "overrides": {
         "machine_width": { "default": 205 },
         "machine_height": { "default": 200 },