diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/pack/DeltaStreamTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/pack/DeltaStreamTest.java
index 9b34ad5e0..3f3038b42 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/pack/DeltaStreamTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/pack/DeltaStreamTest.java
@@ -249,12 +249,29 @@ private void assertValidState() throws IOException {
 		assertEquals(data.length, BinaryDelta.getResultSize(delta));
 		assertTrue(Arrays.equals(data, BinaryDelta.apply(base, delta)));
 
+		// Assert that a single bulk read produces the correct result.
+		//
 		byte[] act = new byte[data.length];
 		DeltaStream in = open();
 		assertEquals(data.length, in.getSize());
 		assertEquals(data.length, in.read(act));
 		assertEquals(-1, in.read());
-		assertTrue(Arrays.equals(data, act));
+		assertTrue("bulk read has same content", Arrays.equals(data, act));
+
+		// Assert that smaller tiny reads have the same result too.
+		//
+		act = new byte[data.length];
+		in = open();
+		int read = 0;
+		while (read < data.length) {
+			int n = in.read(act, read, 128);
+			if (n <= 0)
+				break;
+			read += n;
+		}
+		assertEquals(data.length, read);
+		assertEquals(-1, in.read());
+		assertTrue("small reads have same content", Arrays.equals(data, act));
 	}
 
 	private DeltaStream open() throws IOException {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/DeltaStream.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/DeltaStream.java
index 6f479eb90..72015d94e 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/DeltaStream.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/pack/DeltaStream.java
@@ -215,7 +215,8 @@ public int read(byte[] buf, int off, int len) throws IOException {
 				if (n < 0)
 					throw new CorruptObjectException(
 							JGitText.get().baseLengthIncorrect);
-				baseOffset += n;
+				copyOffset += n;
+				baseOffset = copyOffset;
 				break;
 
 			case CMD_INSERT:
@@ -225,6 +226,7 @@ public int read(byte[] buf, int off, int len) throws IOException {
 
 			case CMD_EOF:
 				return 0 < act ? act : -1;
+
 			default:
 				throw new CorruptObjectException(
 						JGitText.get().unsupportedCommand0);