diff --git a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/ondisk/OnDiskInvertedIndex.java b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/ondisk/OnDiskInvertedIndex.java
index 69e57be..2fd5d63 100644
--- a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/ondisk/OnDiskInvertedIndex.java
+++ b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/ondisk/OnDiskInvertedIndex.java
@@ -15,6 +15,8 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.ondisk;
 
+import java.io.DataOutput;
+import java.io.IOException;
 import java.nio.ByteBuffer;
 
 import edu.uci.ics.hyracks.api.context.IHyracksCommonContext;
@@ -69,13 +71,12 @@
 public class OnDiskInvertedIndex implements IInvertedIndex {
     private final IHyracksCommonContext ctx = new DefaultHyracksCommonContext();
 
-    // Schema of BTree tuples.
-    public final int TOKEN_FIELD = 0;
-    public final int INVLIST_START_PAGE_ID_FIELD = 1;
-    public final int INVLIST_END_PAGE_ID_FIELD = 2;
-    public final int INVLIST_START_OFF_FIELD = 3;
-    public final int INVLIST_NUM_ELEMENTS_FIELD = 4;
-
+    // Schema of BTree tuples, set in constructor.    
+    public final int invListStartPageIdField;
+    public final int invListEndPageIdField;
+    public final int invListStartOffField;
+    public final int invListNumElementsField;
+    
     // Type traits to be appended to the token type trait which finally form the BTree field type traits.
     private static final ITypeTraits[] btreeValueTypeTraits = new ITypeTraits[4];
     static {
@@ -104,7 +105,6 @@
     private final FileReference invListsFile;
     // Last page id of inverted-lists file (inclusive). Set during bulk load.
     private int invListsMaxPageId = -1;
-
     private boolean isOpen = false;
 
     public OnDiskInvertedIndex(IBufferCache bufferCache, IFileMapProvider fileMapProvider,
@@ -124,6 +124,10 @@
         this.numTokenFields = btree.getComparatorFactories().length;
         this.numInvListKeys = invListCmpFactories.length;
         this.invListsFile = invListsFile;
+        this.invListStartPageIdField = numTokenFields;
+        this.invListEndPageIdField = numTokenFields + 1;
+        this.invListStartOffField = numTokenFields + 2;
+        this.invListNumElementsField = numTokenFields + 3;
     }
 
     @Override
@@ -260,16 +264,16 @@
                 ctx.btreeCursor.next();
                 ITupleReference frameTuple = ctx.btreeCursor.getTuple();
                 int startPageId = IntegerSerializerDeserializer.getInt(
-                        frameTuple.getFieldData(INVLIST_START_PAGE_ID_FIELD),
-                        frameTuple.getFieldStart(INVLIST_START_PAGE_ID_FIELD));
+                        frameTuple.getFieldData(invListStartPageIdField),
+                        frameTuple.getFieldStart(invListStartPageIdField));
                 int endPageId = IntegerSerializerDeserializer.getInt(
-                        frameTuple.getFieldData(INVLIST_END_PAGE_ID_FIELD),
-                        frameTuple.getFieldStart(INVLIST_END_PAGE_ID_FIELD));
-                int startOff = IntegerSerializerDeserializer.getInt(frameTuple.getFieldData(INVLIST_START_OFF_FIELD),
-                        frameTuple.getFieldStart(INVLIST_START_OFF_FIELD));
+                        frameTuple.getFieldData(invListEndPageIdField),
+                        frameTuple.getFieldStart(invListEndPageIdField));
+                int startOff = IntegerSerializerDeserializer.getInt(frameTuple.getFieldData(invListStartOffField),
+                        frameTuple.getFieldStart(invListStartOffField));
                 int numElements = IntegerSerializerDeserializer.getInt(
-                        frameTuple.getFieldData(INVLIST_NUM_ELEMENTS_FIELD),
-                        frameTuple.getFieldStart(INVLIST_NUM_ELEMENTS_FIELD));
+                        frameTuple.getFieldData(invListNumElementsField),
+                        frameTuple.getFieldStart(invListNumElementsField));
                 listCursor.reset(startPageId, endPageId, startOff, numElements);
             } else {
                 listCursor.reset(0, 0, 0, 0);
@@ -330,14 +334,26 @@
         private void createAndInsertBTreeTuple() throws IndexException, HyracksDataException {
             // Build tuple.        
             btreeTupleBuilder.reset();
-            btreeTupleBuilder.addField(lastTuple.getFieldData(0), lastTuple.getFieldStart(0),
-                    lastTuple.getFieldLength(0));
-            // TODO: Boxing integers here. Fix it.
-            btreeTupleBuilder.addField(IntegerSerializerDeserializer.INSTANCE, currentInvListStartPageId);
-            btreeTupleBuilder.addField(IntegerSerializerDeserializer.INSTANCE, currentPageId);
-            btreeTupleBuilder.addField(IntegerSerializerDeserializer.INSTANCE, currentInvListStartOffset);
-            btreeTupleBuilder.addField(IntegerSerializerDeserializer.INSTANCE, invListBuilder.getListSize());
-            // Reset tuple reference and add it.
+            DataOutput output = btreeTupleBuilder.getDataOutput();
+            // Add key fields.
+            for (int i = 0; i < numTokenFields; i++) {
+                btreeTupleBuilder.addField(lastTuple.getFieldData(i), lastTuple.getFieldStart(i),
+                        lastTuple.getFieldLength(i));
+            }
+            // Add inverted-list 'pointer' value fields.
+            try {
+                output.writeInt(currentInvListStartPageId);
+                btreeTupleBuilder.addFieldEndOffset();
+                output.writeInt(currentPageId);
+                btreeTupleBuilder.addFieldEndOffset();
+                output.writeInt(currentInvListStartOffset);
+                btreeTupleBuilder.addFieldEndOffset();
+                output.writeInt(invListBuilder.getListSize());
+                btreeTupleBuilder.addFieldEndOffset();
+            } catch (IOException e) {
+                throw new HyracksDataException(e);
+            }
+            // Reset tuple reference and add it into the BTree load.
             btreeTupleReference.reset(btreeTupleBuilder.getFieldEndOffsets(), btreeTupleBuilder.getByteArray());
             btreeBulkloader.add(btreeTupleReference);
         }