diff --git a/include/vfw.h b/include/vfw.h
index aae8b1f878..b3b6679ebf 100644
--- a/include/vfw.h
+++ b/include/vfw.h
@@ -822,7 +822,9 @@ typedef struct {
 #define AVIIF_LIST	0x00000001	/* chunk is a 'LIST' */
 #define AVIIF_TWOCC	0x00000002
 #define AVIIF_KEYFRAME	0x00000010	/* this frame is a key frame. */
-
+#define AVIIF_FIRSTPART 0x00000020
+#define AVIIF_LASTPART  0x00000040
+#define AVIIF_MIDPART   (AVIIF_LASTPART|AVIIF_FIRSTPART)
 #define AVIIF_NOTIME	0x00000100	/* this frame doesn't take any time */
 #define AVIIF_COMPUSE	0x0FFF0000