diff --git a/includes/sanitizers/class-amp-img-sanitizer.php b/includes/sanitizers/class-amp-img-sanitizer.php
index 90908a17414..4f4169b729d 100644
--- a/includes/sanitizers/class-amp-img-sanitizer.php
+++ b/includes/sanitizers/class-amp-img-sanitizer.php
@@ -119,7 +119,6 @@ private function filter_attributes( $attributes ) {
 				case 'alt':
 				case 'class':
 				case 'srcset':
-				case 'sizes':
 				case 'on':
 				case 'attribution':
 					$out[ $name ] = $value;