diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/UnpackedObject.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/UnpackedObject.java
index 4065019dc..b04a294b6 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/UnpackedObject.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/UnpackedObject.java
@@ -328,6 +328,7 @@ private static int readSome(InputStream in, final byte[] hdr, int off,
 			if (n < 0)
 				break;
 			avail += n;
+			off += n;
 			cnt -= n;
 		}
 		return avail;