diff --git a/CHANGES.txt b/CHANGES.txt
index f851f5f80fe..2488db37e5d 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -568,6 +568,8 @@ Release 0.21.0 - Unreleased
    HBASE-3059  TestReadWriteConsistencyControl occasionally hangs (Hairong 
    	       via Ryan)
    HBASE-2906  [rest/stargate] URI decoding in RowResource
+   HBASE-3008  Memstore.updateColumnValue passes wrong flag to heapSizeChange
+   	       (Causes memstore size to go negative)
 
   IMPROVEMENTS
    HBASE-1760  Cleanup TODOs in HTable
diff --git a/src/main/java/org/apache/hadoop/hbase/KeyValue.java b/src/main/java/org/apache/hadoop/hbase/KeyValue.java
index 6ab3f5dea03..5dd9e325264 100644
--- a/src/main/java/org/apache/hadoop/hbase/KeyValue.java
+++ b/src/main/java/org/apache/hadoop/hbase/KeyValue.java
@@ -1933,7 +1933,6 @@ public class KeyValue implements Writable, HeapSize {
         ClassSize.align(ClassSize.ARRAY) + ClassSize.align(length) +
         (3 * Bytes.SIZEOF_INT) +
         ClassSize.align(ClassSize.ARRAY) +
-        ClassSize.align((rowCache == null ? 0 : rowCache.length)) +
         (2 * Bytes.SIZEOF_LONG));
   }
 
diff --git a/src/test/java/org/apache/hadoop/hbase/regionserver/TestHRegion.java b/src/test/java/org/apache/hadoop/hbase/regionserver/TestHRegion.java
index 8ed20b18695..7631b5af407 100644
--- a/src/test/java/org/apache/hadoop/hbase/regionserver/TestHRegion.java
+++ b/src/test/java/org/apache/hadoop/hbase/regionserver/TestHRegion.java
@@ -1958,6 +1958,22 @@ public class TestHRegion extends HBaseTestCase {
     assertICV(row, fam1, qual1, value+amount);
   }
 
+  public void testIncrementColumnValue_heapSize() throws IOException {
+    EnvironmentEdgeManagerTestHelper.injectEdge(new IncrementingEnvironmentEdge());
+
+    initHRegion(tableName, getName(), fam1);
+
+    long byAmount = 1L;
+    long size;
+
+    for( int i = 0; i < 1000 ; i++) {
+      region.incrementColumnValue(row, fam1, qual1, byAmount, true);
+
+      size = region.memstoreSize.get();
+      assertTrue("memstore size: " + size, size >= 0);
+    }
+  }
+
   public void testIncrementColumnValue_UpdatingInPlace_Negative()
     throws IOException {
     initHRegion(tableName, getName(), fam1);
diff --git a/src/test/java/org/apache/hadoop/hbase/regionserver/TestStore.java b/src/test/java/org/apache/hadoop/hbase/regionserver/TestStore.java
index 377e6b14ce0..d436e2ec8d3 100644
--- a/src/test/java/org/apache/hadoop/hbase/regionserver/TestStore.java
+++ b/src/test/java/org/apache/hadoop/hbase/regionserver/TestStore.java
@@ -53,6 +53,7 @@ import org.apache.hadoop.hbase.regionserver.wal.HLog;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManagerTestHelper;
+import org.apache.hadoop.hbase.util.IncrementingEnvironmentEdge;
 import org.apache.hadoop.hbase.util.ManualEnvironmentEdge;
 import org.apache.hadoop.security.UnixUserGroupInformation;
 
@@ -69,6 +70,7 @@ public class TestStore extends TestCase {
   byte [] family = Bytes.toBytes("family");
 
   byte [] row = Bytes.toBytes("row");
+  byte [] row2 = Bytes.toBytes("row2");
   byte [] qf1 = Bytes.toBytes("qf1");
   byte [] qf2 = Bytes.toBytes("qf2");
   byte [] qf3 = Bytes.toBytes("qf3");
@@ -332,6 +334,62 @@ public class TestStore extends TestCase {
     assertEquals(oldValue, Bytes.toLong(results.get(1).getValue()));
   }
 
+  public void testICV_negMemstoreSize()  throws IOException {
+      init(this.getName());
+
+    long time = 100;
+    ManualEnvironmentEdge ee = new ManualEnvironmentEdge();
+    ee.setValue(time);
+    EnvironmentEdgeManagerTestHelper.injectEdge(ee);
+    long newValue = 3L;
+    long size = 0;
+
+
+    size += this.store.add(new KeyValue(Bytes.toBytes("200909091000"), family, qf1,
+        System.currentTimeMillis(),
+        Bytes.toBytes(newValue)));
+    size += this.store.add(new KeyValue(Bytes.toBytes("200909091200"), family, qf1,
+        System.currentTimeMillis(),
+        Bytes.toBytes(newValue)));
+    size += this.store.add(new KeyValue(Bytes.toBytes("200909091300"), family, qf1,
+        System.currentTimeMillis(),
+        Bytes.toBytes(newValue)));
+    size += this.store.add(new KeyValue(Bytes.toBytes("200909091400"), family, qf1,
+        System.currentTimeMillis(),
+        Bytes.toBytes(newValue)));
+    size += this.store.add(new KeyValue(Bytes.toBytes("200909091500"), family, qf1,
+        System.currentTimeMillis(),
+        Bytes.toBytes(newValue)));
+
+
+    for ( int i = 0 ; i < 10000 ; ++i) {
+      newValue++;
+
+      long ret = this.store.updateColumnValue(row, family, qf1, newValue);
+      long ret2 = this.store.updateColumnValue(row2, family, qf1, newValue);
+
+      if (ret != 0) System.out.println("ret: " + ret);
+      if (ret2 != 0) System.out.println("ret2: " + ret2);
+
+      assertTrue("ret: " + ret, ret >= 0);
+      size += ret;
+      assertTrue("ret2: " + ret2, ret2 >= 0);
+      size += ret2;
+
+
+      if (i % 1000 == 0)
+        ee.setValue(++time);
+    }
+
+    long computedSize=0;
+    for (KeyValue kv : this.store.memstore.kvset) {
+      long kvsize = this.store.memstore.heapSizeChange(kv, true);
+      //System.out.println(kv + " size= " + kvsize + " kvsize= " + kv.heapSize());
+      computedSize += kvsize;
+    }
+    assertEquals(computedSize, size);
+  }
+
   public void testIncrementColumnValue_SnapshotFlushCombo() throws Exception {
     ManualEnvironmentEdge mee = new ManualEnvironmentEdge();
     EnvironmentEdgeManagerTestHelper.injectEdge(mee);