diff --git a/includes/class-amp-theme-support.php b/includes/class-amp-theme-support.php
index 0f77106decd..23834f345e6 100644
--- a/includes/class-amp-theme-support.php
+++ b/includes/class-amp-theme-support.php
@@ -1809,7 +1809,18 @@ public static function prepare_response( $response, $args = [] ) {
 				$response
 			)
 		) ) {
-			if ( AMP_Validation_Manager::$is_validate_request ) {
+			// Detect whether redirect happened and prevent failing a validation request when that happens,
+			// since \AMP_Validation_Manager::validate_url() follows redirects.
+			$sent_location_header = false;
+			foreach ( headers_list() as $sent_header ) {
+				if ( preg_match( '#^location:#i', $sent_header ) ) {
+					$sent_location_header = true;
+					break;
+				}
+			}
+			$did_redirect = $status_code >= 300 && $status_code < 400 && $sent_location_header;
+
+			if ( AMP_Validation_Manager::$is_validate_request && ! $did_redirect ) {
 				if ( ! headers_sent() ) {
 					status_header( 400 );
 					header( 'Content-Type: application/json; charset=utf-8' );
diff --git a/src/Infrastructure/ServiceBasedPlugin.php b/src/Infrastructure/ServiceBasedPlugin.php
index abf6ba12380..fd301acad56 100644
--- a/src/Infrastructure/ServiceBasedPlugin.php
+++ b/src/Infrastructure/ServiceBasedPlugin.php
@@ -293,7 +293,7 @@ protected function register_service( $id, $class ) {
 
 		$this->service_container->put( $id, $service );
 
-		if ( $service instanceof CliCommand && is_callable( $service ) && defined( 'WP_CLI' ) && WP_CLI ) {
+		if ( $service instanceof CliCommand && defined( 'WP_CLI' ) && WP_CLI ) {
 			WP_CLI::add_command( $service::get_command_name(), $service );
 		}