diff --git a/src/main/java/com/falsepattern/endlessids/asm/transformer/FmlRegistry.java b/src/main/java/com/falsepattern/endlessids/asm/transformer/FmlRegistry.java
index c22815e..f92ea21 100644
--- a/src/main/java/com/falsepattern/endlessids/asm/transformer/FmlRegistry.java
+++ b/src/main/java/com/falsepattern/endlessids/asm/transformer/FmlRegistry.java
@@ -22,7 +22,7 @@ public class FmlRegistry implements IClassNodeTransformer {
         }
         field = AsmUtil.findField(cn, "MAX_ITEM_ID", true);
         if (field != null) {
-            field.value = ExtendedConstants.maxBlockID;
+            field.value = ExtendedConstants.maxItemID;
         }
         boolean found = false;
         for (final MethodNode method : cn.methods) {
@@ -30,7 +30,7 @@ public class FmlRegistry implements IClassNodeTransformer {
                                                    ExtendedConstants.maxBlockID, true)) {
                 found = true;
             }
-            AsmUtil.transformInlinedSizeMethod(cn, method, 31999, ExtendedConstants.maxBlockID, true);
+            AsmUtil.transformInlinedSizeMethod(cn, method, 31999, ExtendedConstants.maxItemID, true);
         }
         if (!found) {
             throw new AsmTransformException("can't find 4095 constant in any method");
diff --git a/src/main/java/com/falsepattern/endlessids/constants/ExtendedConstants.java b/src/main/java/com/falsepattern/endlessids/constants/ExtendedConstants.java
index f7a598a..8435e60 100644
--- a/src/main/java/com/falsepattern/endlessids/constants/ExtendedConstants.java
+++ b/src/main/java/com/falsepattern/endlessids/constants/ExtendedConstants.java
@@ -24,6 +24,9 @@ public class ExtendedConstants {
     public static final int blockIDCount = 1 << (bitsPerID - countCorrectionBits);
     public static final int maxBlockID = blockIDCount - 1;
 
+    public static final int itemIDCount = 1 << (bitsPerID);
+    public static final int maxItemID = itemIDCount - 1;
+
     public static final int bitsPerBlock = 8 + bitsPerID + bitsPerMetadata;
     public static final int nibblesPerBlock = bitsPerBlock / 4;
     public static final int nibblesPerEBS = nibblesPerBlock * 16 * 16 * 16;