diff --git a/image_properties.h b/image_properties.h
index 6026c2e..ba6ce44 100644
--- a/image_properties.h
+++ b/image_properties.h
@@ -37,6 +37,10 @@
   // The product version of this image.
   std::string version;
 
+  // A unique string that identifies this build. Normally a combination of the
+  // the version, signing keys and build target.
+  std::string build_fingerprint;
+
   // The board name this image was built for.
   std::string board;