diff --git a/sdk/update.go b/sdk/update.go
index 389e845..5db604b 100644
--- a/sdk/update.go
+++ b/sdk/update.go
@@ -281,6 +281,10 @@
 	return append(variants, newVariant)
 }
 
+// BUILD_NUMBER_FILE is the name of the file in the snapshot zip that will contain the number of
+// the build from which the snapshot was produced.
+const BUILD_NUMBER_FILE = "snapshot-creation-build-number.txt"
+
 // SDK directory structure
 // <sdk_root>/
 //     Android.bp   : definition of a 'sdk' module is here. This is a hand-made one.
@@ -479,6 +483,9 @@
 
 	bp.build(pctx, ctx, nil)
 
+	// Copy the build number file into the snapshot.
+	builder.CopyToSnapshot(ctx.Config().BuildNumberFile(ctx), BUILD_NUMBER_FILE)
+
 	filesToZip := builder.filesToZip
 
 	// zip them all