diff --git a/visionforge-fx/src/main/kotlin/space/kscience/visionforge/solid/FX3DPlugin.kt b/visionforge-fx/src/main/kotlin/space/kscience/visionforge/solid/FX3DPlugin.kt
index 84dcb31d..9aed5d50 100644
--- a/visionforge-fx/src/main/kotlin/space/kscience/visionforge/solid/FX3DPlugin.kt
+++ b/visionforge-fx/src/main/kotlin/space/kscience/visionforge/solid/FX3DPlugin.kt
@@ -150,7 +150,7 @@ public interface FX3DFactory<in T : Solid> {
     public operator fun invoke(obj: T, binding: VisualObjectFXBinding): Node
 
     public companion object {
-        public const val TYPE = "fx3DFactory"
+        public const val TYPE: String = "fx3DFactory"
     }
 }