diff --git a/resources/definitions/ultimaker3.def.json b/resources/definitions/ultimaker3.def.json
index 9428b89f0f..5d974cb4e3 100644
--- a/resources/definitions/ultimaker3.def.json
+++ b/resources/definitions/ultimaker3.def.json
@@ -140,7 +140,7 @@
         "raft_margin": { "value": "10" },
         "raft_surface_layers": { "value": "1" },
         "retraction_amount": { "value": "6.5" },
-        "retraction_combing": {"value": "no_outer_surfaces"},
+        "retraction_combing": {"value": "'no_outer_surfaces'"},
         "retraction_count_max": { "value": "10" },
         "retraction_extrusion_window": { "value": "1" },
         "retraction_hop": { "value": "2" },