diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/api/IItemDefinition.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/api/IItemDefinition.kt
index 1a062f8a..1c293b3a 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/api/IItemDefinition.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/api/IItemDefinition.kt
@@ -31,7 +31,7 @@ interface IItemDefinition : IThingWithDescription {
 	/**
 	 * Категория предмета, определяет, в какую вкладку инвентаря оно попадает
 	 */
-	val category: String
+	val category: String?
 
 	/**
 	 * Иконка в инвентаре, относительный и абсолютный пути
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/impl/ItemDefinition.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/impl/ItemDefinition.kt
index 873fc0e4..57ad5746 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/impl/ItemDefinition.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/impl/ItemDefinition.kt
@@ -16,24 +16,24 @@ data class ItemDefinition(
 	@JsonFlat
 	val descriptionData: ThingDescription,
 
-	override var itemName: String,
-	override var price: Long = 0,
-	override var rarity: ItemRarity = ItemRarity.COMMON,
-	override var category: String,
-	override var inventoryIcon: ImmutableList<IInventoryIcon>? = null,
-	override var itemTags: ImmutableList<String> = ImmutableList.of(),
-	override var learnBlueprintsOnPickup: ImmutableList<RegistryReference<IItemDefinition>> = ImmutableList.of(),
-	override var maxStack: Long = 9999L,
-	override var eventCategory: String? = null,
-	override var consumeOnPickup: Boolean = false,
-	override var pickupQuestTemplates: ImmutableList<String> = ImmutableList.of(),
-	override var tooltipKind: String = "normal",
-	override var twoHanded: Boolean = false,
-	override var radioMessagesOnPickup: ImmutableList<String> = ImmutableList.of(),
-	override var fuelAmount: Long = 0,
-	override var pickupSoundsSmall: ImmutableList<String> = ImmutableList.of(),
-	override var pickupSoundsMedium: ImmutableList<String> = ImmutableList.of(),
-	override var pickupSoundsLarge: ImmutableList<String> = ImmutableList.of(),
-	override var smallStackLimit: Long? = null,
-	override var mediumStackLimit: Long? = null,
+	override val itemName: String,
+	override val price: Long = 0,
+	override val rarity: ItemRarity = ItemRarity.COMMON,
+	override val category: String? = null,
+	override val inventoryIcon: ImmutableList<IInventoryIcon>? = null,
+	override val itemTags: ImmutableList<String> = ImmutableList.of(),
+	override val learnBlueprintsOnPickup: ImmutableList<RegistryReference<IItemDefinition>> = ImmutableList.of(),
+	override val maxStack: Long = 9999L,
+	override val eventCategory: String? = null,
+	override val consumeOnPickup: Boolean = false,
+	override val pickupQuestTemplates: ImmutableList<String> = ImmutableList.of(),
+	override val tooltipKind: String = "normal",
+	override val twoHanded: Boolean = false,
+	override val radioMessagesOnPickup: ImmutableList<String> = ImmutableList.of(),
+	override val fuelAmount: Long = 0,
+	override val pickupSoundsSmall: ImmutableList<String> = ImmutableList.of(),
+	override val pickupSoundsMedium: ImmutableList<String> = ImmutableList.of(),
+	override val pickupSoundsLarge: ImmutableList<String> = ImmutableList.of(),
+	override val smallStackLimit: Long? = null,
+	override val mediumStackLimit: Long? = null,
 ) : IItemDefinition, IThingWithDescription by descriptionData