diff --git a/mkbootimg.py b/mkbootimg.py
index 9682033..00a4623 100644
--- a/mkbootimg.py
+++ b/mkbootimg.py
@@ -64,7 +64,7 @@
 
 
 def write_header_v3(args):
-    BOOT_IMAGE_HEADER_V3_SIZE = 1596
+    BOOT_IMAGE_HEADER_V3_SIZE = 1580
     BOOT_MAGIC = 'ANDROID!'.encode()
 
     args.output.write(pack('8s', BOOT_MAGIC))