diff --git a/tools/applypatch/imgdiff.h b/tools/applypatch/imgdiff.h
index 7ec45c5..f2069b4 100644
--- a/tools/applypatch/imgdiff.h
+++ b/tools/applypatch/imgdiff.h
@@ -15,8 +15,10 @@
  */
 
 // Image patch chunk types
-#define CHUNK_NORMAL 0
-#define CHUNK_GZIP   1
+#define CHUNK_NORMAL   0
+#define CHUNK_GZIP     1   // version 1 only
+#define CHUNK_DEFLATE  2   // version 2 only
+#define CHUNK_RAW      3   // version 2 only
 
 // The gzip header size is actually variable, but we currently don't
 // support gzipped data with any of the optional fields, so for now it