diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/PackWriterTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/PackWriterTest.java
index 7a829dee0..20e32b22c 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/PackWriterTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/PackWriterTest.java
@@ -58,7 +58,6 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
-import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -125,9 +124,11 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 
 	/**
 	 * Test constructor for exceptions, default settings, initialization.
+	 *
+	 * @throws IOException
 	 */
 	@Test
-	public void testContructor() {
+	public void testContructor() throws IOException {
 		writer = new PackWriter(config, db.newObjectReader());
 		assertEquals(false, writer.isDeltaBaseAsOffset());
 		assertEquals(true, config.isReuseDeltas());
@@ -177,7 +178,7 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 	 */
 	@Test
 	public void testWriteEmptyPack2() throws IOException {
-		createVerifyOpenPack(EMPTY_LIST_REVS.iterator());
+		createVerifyOpenPack(EMPTY_LIST_REVS);
 
 		assertEquals(0, writer.getObjectsNumber());
 		assertEquals(0, pack.getObjectCount());
@@ -320,7 +321,7 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 		for (int i = 0; i < forcedOrder.length; i++)
 			forcedOrderRevs[i] = parser.parseAny(forcedOrder[i]);
 
-		createVerifyOpenPack(Arrays.asList(forcedOrderRevs).iterator());
+		createVerifyOpenPack(Arrays.asList(forcedOrderRevs));
 
 		assertEquals(forcedOrder.length, writer.getObjectsNumber());
 		verifyObjectsOrder(forcedOrder);
@@ -544,11 +545,12 @@ public class PackWriterTest extends SampleDataRepositoryTestCase {
 		verifyOpenPack(thin);
 	}
 
-	private void createVerifyOpenPack(final Iterator<RevObject> objectSource)
+	private void createVerifyOpenPack(final List<RevObject> objectSource)
 			throws MissingObjectException, IOException {
 		NullProgressMonitor m = NullProgressMonitor.INSTANCE;
 		writer = new PackWriter(config, db.newObjectReader());
-		writer.preparePack(objectSource);
+		writer.preparePack(objectSource.iterator());
+		assertEquals(objectSource.size(), writer.getObjectsNumber());
 		writer.writePack(m, m, os);
 		writer.release();
 		verifyOpenPack(false);
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackWriter.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackWriter.java
index 2eb2700dd..5039eed2a 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackWriter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/PackWriter.java
@@ -402,8 +402,18 @@ public class PackWriter {
 	 * Returns objects number in a pack file that was created by this writer.
 	 *
 	 * @return number of objects in pack.
+	 * @throws IOException
+	 *             a cached pack cannot supply its object count.
 	 */
-	public long getObjectsNumber() {
+	public long getObjectsNumber() throws IOException {
+		if (stats.totalObjects == 0) {
+			long objCnt = 0;
+			for (List<ObjectToPack> list : objectsLists)
+				objCnt += list.size();
+			for (CachedPack pack : cachedPacks)
+				objCnt += pack.getObjectCount();
+			return objCnt;
+		}
 		return stats.totalObjects;
 	}
 
@@ -635,13 +645,8 @@ public class PackWriter {
 		final PackOutputStream out = new PackOutputStream(writeMonitor,
 				packStream, this);
 
-		long objCnt = 0;
-		for (List<ObjectToPack> list : objectsLists)
-			objCnt += list.size();
-		for (CachedPack pack : cachedPacks)
-			objCnt += pack.getObjectCount();
+		long objCnt = getObjectsNumber();
 		stats.totalObjects = objCnt;
-
 		writeMonitor.beginTask(JGitText.get().writingObjects, (int) objCnt);
 		long writeStart = System.currentTimeMillis();