diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_10to1_11/packets/BlockItemPackets1_11.java b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_10to1_11/packets/BlockItemPackets1_11.java
index 28e27957..e377cd59 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_10to1_11/packets/BlockItemPackets1_11.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_10to1_11/packets/BlockItemPackets1_11.java
@@ -62,7 +62,7 @@ public class BlockItemPackets1_11 extends LegacyBlockItemRewriter<Protocol1_10To
         protocol.registerClientbound(ClientboundPackets1_9_3.SET_SLOT, new PacketRemapper() {
             @Override
             public void registerMap() {
-                map(Type.BYTE); // 0 - Window ID
+                map(Type.UNSIGNED_BYTE); // 0 - Window ID
                 map(Type.SHORT); // 1 - Slot ID
                 map(Type.ITEM); // 2 - Slot Value
 
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_12_2to1_13/packets/BlockItemPackets1_13.java b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_12_2to1_13/packets/BlockItemPackets1_13.java
index 54e9cdcb..fde6d1f6 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_12_2to1_13/packets/BlockItemPackets1_13.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_12_2to1_13/packets/BlockItemPackets1_13.java
@@ -271,7 +271,7 @@ public class BlockItemPackets1_13 extends com.viaversion.viabackwards.api.rewrit
         protocol.registerClientbound(ClientboundPackets1_13.SET_SLOT, new PacketRemapper() {
             @Override
             public void registerMap() {
-                map(Type.BYTE);
+                map(Type.UNSIGNED_BYTE);
                 map(Type.SHORT);
                 map(Type.FLAT_ITEM, Type.ITEM);
 
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_13_1to1_13_2/packets/InventoryPackets1_13_2.java b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_13_1to1_13_2/packets/InventoryPackets1_13_2.java
index 771189fd..330a099c 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_13_1to1_13_2/packets/InventoryPackets1_13_2.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_13_1to1_13_2/packets/InventoryPackets1_13_2.java
@@ -31,7 +31,7 @@ public class InventoryPackets1_13_2 {
         protocol.registerClientbound(ClientboundPackets1_13.SET_SLOT, new PacketRemapper() {
             @Override
             public void registerMap() {
-                map(Type.BYTE); // 0 - Window ID
+                map(Type.UNSIGNED_BYTE); // 0 - Window ID
                 map(Type.SHORT); // 1 - Slot ID
                 map(Type.FLAT_VAR_INT_ITEM, Type.FLAT_ITEM); // 2 - Slot Value
             }