diff --git a/validator/validator-main.protoascii b/validator/validator-main.protoascii
index 7bc883b7f055..8b2424bcf8c9 100644
--- a/validator/validator-main.protoascii
+++ b/validator/validator-main.protoascii
@@ -25,7 +25,7 @@ min_validator_revision_required: 295
 # newer versions of the spec file. This is currently a Google internal
 # mechanism, validator.js does not use this facility. However, any
 # change to this file (validator-main.js) requires updating this revision id.
-spec_file_revision: 554
+spec_file_revision: 557
 
 styles_spec_url: "https://www.ampproject.org/docs/guides/author-develop/responsive/style_pages"
 script_spec_url: "https://www.ampproject.org/docs/reference/spec#html-tags"