diff --git a/data/1.16.201/protocol.json b/data/1.16.201/protocol.json
index 2dd5be8..361d139 100644
--- a/data/1.16.201/protocol.json
+++ b/data/1.16.201/protocol.json
@@ -4531,7 +4531,7 @@
       [
         {
           "name": "window_id",
-          "type": "u8"
+          "type": "WindowID"
         },
         {
           "name": "window_type",
@@ -4552,7 +4552,7 @@
       [
         {
           "name": "window_id",
-          "type": "u8"
+          "type": "WindowID"
         },
         {
           "name": "server",
@@ -4595,7 +4595,7 @@
       [
         {
           "name": "window_id",
-          "type": "varint"
+          "type": "WindowID"
         },
         {
           "name": "slot",
@@ -5481,7 +5481,7 @@
       [
         {
           "name": "window_id",
-          "type": "u8"
+          "type": "WindowID"
         },
         {
           "name": "window_type",
@@ -5526,7 +5526,7 @@
       [
         {
           "name": "window_id",
-          "type": "u8"
+          "type": "WindowID"
         },
         {
           "name": "window_type",
diff --git a/data/1.16.210/protocol.json b/data/1.16.210/protocol.json
index fe48767..27a31ae 100644
--- a/data/1.16.210/protocol.json
+++ b/data/1.16.210/protocol.json
@@ -2546,6 +2546,41 @@
         }
       }
     ],
+    "WindowIDVarint": [
+      "mapper",
+      {
+        "type": "varint",
+        "mappings": {
+          "0": "inventory",
+          "1": "first",
+          "100": "last",
+          "119": "offhand",
+          "120": "armor",
+          "121": "creative",
+          "122": "hotbar",
+          "123": "fixed_inventory",
+          "124": "ui",
+          "-100": "drop_contents",
+          "-24": "beacon",
+          "-23": "trading_output",
+          "-22": "trading_use_inputs",
+          "-21": "trading_input_2",
+          "-20": "trading_input_1",
+          "-17": "enchant_output",
+          "-16": "enchant_material",
+          "-15": "enchant_input",
+          "-13": "anvil_output",
+          "-12": "anvil_result",
+          "-11": "anvil_material",
+          "-10": "container_input",
+          "-5": "crafting_use_ingredient",
+          "-4": "crafting_result",
+          "-3": "crafting_remove_ingredient",
+          "-2": "crafting_add_ingredient",
+          "-1": "none"
+        }
+      }
+    ],
     "WindowType": [
       "mapper",
       {
@@ -4672,7 +4707,7 @@
       [
         {
           "name": "window_id",
-          "type": "u8"
+          "type": "WindowID"
         },
         {
           "name": "window_type",
@@ -4693,7 +4728,7 @@
       [
         {
           "name": "window_id",
-          "type": "u8"
+          "type": "WindowID"
         },
         {
           "name": "server",
@@ -4736,7 +4771,7 @@
       [
         {
           "name": "window_id",
-          "type": "varint"
+          "type": "WindowIDVarint"
         },
         {
           "name": "slot",
@@ -5653,7 +5688,7 @@
       [
         {
           "name": "window_id",
-          "type": "u8"
+          "type": "WindowID"
         },
         {
           "name": "window_type",
@@ -5698,7 +5733,7 @@
       [
         {
           "name": "window_id",
-          "type": "u8"
+          "type": "WindowID"
         },
         {
           "name": "window_type",
diff --git a/data/latest/proto.yml b/data/latest/proto.yml
index f24b5fb..713dfff 100644
--- a/data/latest/proto.yml
+++ b/data/latest/proto.yml
@@ -896,7 +896,7 @@ packet_container_open:
    !bound: client
    # WindowID is the ID representing the window that is being opened. It may be used later to close the
    # container using a ContainerClose packet.
-   window_id: u8
+   window_id: WindowID
    # ContainerType is the type ID of the container that is being opened when opening the container at the
    # position of the packet. It depends on the block/entity, and could, for example, be the window type of
    # a chest or a hopper, but also a horse inventory.
@@ -917,7 +917,7 @@ packet_container_close:
    !bound: both
    # WindowID is the ID representing the window of the container that should be closed. It must be equal to
    # the one sent in the ContainerOpen packet to close the designated window.
-   window_id: u8
+   window_id: WindowID
    # ServerSide determines whether or not the container was force-closed by the server. If this value is
    # not set correctly, the client may ignore the packet and respond with a PacketViolationWarning.
    server: bool
@@ -954,7 +954,7 @@ packet_inventory_slot:
    !bound: both
    # WindowID is the ID of the window that the packet modifies. It must point to one of the windows that the
    # client currently has opened.
-   window_id: varint
+   window_id: WindowIDVarint
    # Slot is the index of the slot that the packet modifies. The new item will be set to the slot at this
    # index.
    slot: varint
@@ -1448,7 +1448,7 @@ packet_update_trade:
    !id: 0x50
    !bound: client
    # WindowID is the ID that identifies the trading window that the client currently has opened.
-   window_id: u8
+   window_id: WindowID
    # WindowType is an identifier specifying the type of the window opened. In vanilla, it appears this is
    # always filled out with 15.
    window_type: WindowType
@@ -1486,7 +1486,7 @@ packet_update_equipment:
    !bound: client
    # WindowID is the identifier associated with the window that the UpdateEquip packet concerns. It is the
    # ID sent for the horse inventory that was opened before this packet was sent.
-   window_id: u8
+   window_id: WindowID
    # WindowType is the type of the window that was opened. Generally, this is the type of a horse inventory,
    # as the packet is specifically made for that.
    window_type: WindowType
diff --git a/data/latest/types.yaml b/data/latest/types.yaml
index 1c613d3..6ba41c8 100644
--- a/data/latest/types.yaml
+++ b/data/latest/types.yaml
@@ -996,6 +996,35 @@ WindowID: i8 =>
    123: fixed_inventory
    124: ui
 
+WindowIDVarint: varint =>
+   -100: drop_contents
+   -24: beacon
+   -23: trading_output
+   -22: trading_use_inputs
+   -21: trading_input_2
+   -20: trading_input_1
+   -17: enchant_output
+   -16: enchant_material
+   -15: enchant_input
+   -13: anvil_output
+   -12: anvil_result
+   -11: anvil_material
+   -10: container_input
+   -5: crafting_use_ingredient
+   -4: crafting_result
+   -3: crafting_remove_ingredient
+   -2: crafting_add_ingredient
+   -1: none
+   0: inventory
+   1: first
+   100: last
+   119: offhand
+   120: armor
+   121: creative
+   122: hotbar
+   123: fixed_inventory
+   124: ui
+
 WindowType: u8 =>
    0: container
    1: workbench