diff --git a/lib/blocks.php b/lib/blocks.php
index c62b0ff117e7b7..863e857d2429cf 100644
--- a/lib/blocks.php
+++ b/lib/blocks.php
@@ -57,7 +57,7 @@ function gutenberg_parse_blocks( $content ) {
 	 * If there are no blocks in the content, return a single block, rather
 	 * than wasting time trying to parse the string.
 	 */
-	if ( ! preg_match( '/<!--\s*(wp:|more|noteaser)/', $content ) ) {
+	if ( ! gutenberg_content_has_blocks( $content ) ) {
 		return array(
 			array(
 				'attrs'     => array(),
diff --git a/phpunit/class-parsing-test.php b/phpunit/class-parsing-test.php
index 2f8af3ad35cea7..9c46f8092b0dbb 100644
--- a/phpunit/class-parsing-test.php
+++ b/phpunit/class-parsing-test.php
@@ -58,7 +58,8 @@ function test_parser_output( $html_filename, $parsed_json_filename ) {
 		$html            = self::strip_r( file_get_contents( $html_path ) );
 		$expected_parsed = json_decode( self::strip_r( file_get_contents( $parsed_json_path ) ), true );
 
-		$result = gutenberg_parse_blocks( $html );
+		$parser = new Gutenberg_PEG_Parser;
+		$result = $parser->parse( _gutenberg_utf8_split( $html ) );
 
 		$this->assertEquals(
 			$expected_parsed,