diff --git a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
index 5d1cc11..8b9f9bd 100644
--- a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
+++ b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
@@ -264,12 +264,19 @@
     }
 
     public static class Comparator extends WritableComparator {
+        public final int LEAD_BYTES = 4;
+
         public Comparator() {
             super(KmerBytesWritable.class);
         }
 
         public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
-            return compareBytes(b1, s1, l1, b2, s2, l2);
+            int kmerlength1 = readInt(b1, s1);
+            int kmerlength2 = readInt(b2, s2);
+            if (kmerlength1 == kmerlength2) {
+                return compareBytes(b1, s1 + LEAD_BYTES, l1 - LEAD_BYTES, b2, s2 + LEAD_BYTES, l2 - LEAD_BYTES);
+            }
+            return kmerlength1 - kmerlength2;
         }
     }
 
diff --git a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/VKmerBytesWritable.java b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/VKmerBytesWritable.java
index 28c6c58..a66d408 100644
--- a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/VKmerBytesWritable.java
+++ b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/VKmerBytesWritable.java
@@ -1,7 +1,5 @@
 package edu.uci.ics.genomix.type;
 
-import org.apache.hadoop.io.WritableComparator;
-
 public class VKmerBytesWritable extends KmerBytesWritable {
     /**
      * 
@@ -96,24 +94,4 @@
         setSize(KmerUtil.getByteNumFromK(k));
     }
 
-    public static class Comparator extends WritableComparator {
-        public final int LEAD_BYTES = 4;
-
-        public Comparator() {
-            super(KmerBytesWritable.class);
-        }
-
-        public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
-            int kmerlength1 = readInt(b1, s1);
-            int kmerlength2 = readInt(b2, s2);
-            if (kmerlength1 == kmerlength2) {
-                return compareBytes(b1, s1 + LEAD_BYTES, l1 - LEAD_BYTES, b2, s2 + LEAD_BYTES, l2 - LEAD_BYTES);
-            }
-            return kmerlength1 - kmerlength2;
-        }
-    }
-
-    static { // register this comparator
-        WritableComparator.define(KmerBytesWritable.class, new Comparator());
-    }
 }