diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackFile.java
index d8d986fb0..2bf8160e2 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackFile.java
@@ -468,6 +468,16 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 			// Tiny optimization: Lots of objects are very small deltas or
 			// deflated commits that are likely to fit in the copy buffer.
 			//
+			if (!validate) {
+				long pos = dataOffset;
+				long cnt = dataLength;
+				while (cnt > 0) {
+					final int n = (int) Math.min(cnt, buf.length);
+					readFully(pos, buf, 0, n, curs);
+					pos += n;
+					cnt -= n;
+				}
+			}
 			out.writeHeader(src, inflatedLength);
 			out.write(buf, 0, (int) dataLength);
 		} else {