diff --git a/src/wp-includes/theme.php b/src/wp-includes/theme.php
index 51ef24ada8..a16d8c5e14 100644
--- a/src/wp-includes/theme.php
+++ b/src/wp-includes/theme.php
@@ -1273,8 +1273,12 @@ function add_theme_support( $feature ) {
 
 		case 'html5' :
 			// You can't just pass 'html5', you need to pass an array of types.
-			if ( ! is_array( $args[0] ) )
+			if ( empty( $args[0] ) ) {
+				$args = array( 0 => array( 'comment-list', 'comment-form', 'search-form' ) );
+			} elseif ( ! is_array( $args[0] ) ) {
+				_doing_it_wrong( "add_theme_support( 'html5' )", 'You need to pass an array of types.', '3.6.1' );
 				return false;
+			}
 
 			// Calling 'html5' again merges, rather than overwrites.
 			if ( isset( $_wp_theme_features['html5'] ) )
diff --git a/tests/phpunit/tests/theme/support.php b/tests/phpunit/tests/theme/support.php
index 08666145a2..47f3698525 100644
--- a/tests/phpunit/tests/theme/support.php
+++ b/tests/phpunit/tests/theme/support.php
@@ -85,9 +85,12 @@ class Tests_Theme_Support extends WP_UnitTestCase {
 		remove_theme_support( 'html5' );
 		$this->assertFalse( current_theme_supports( 'html5' ) );
 		$this->assertFalse( current_theme_supports( 'html5', 'comment-form' ) );
-		$this->assertFalse( add_theme_support( 'html5' ) );
-		$this->assertFalse( current_theme_supports( 'html5' ) );
-		$this->assertFalse( current_theme_supports( 'html5', 'comment-form' ) );
+		$this->assertNotSame( false, add_theme_support( 'html5' ) );
+		$this->assertTrue( current_theme_supports( 'html5' ) );
+		$this->assertTrue( current_theme_supports( 'html5', 'comment-form' ) );
+		$this->assertTrue( current_theme_supports( 'html5', 'comment-list' ) );
+		$this->assertTrue( current_theme_supports( 'html5', 'search-form' ) );
+		$this->assertFalse( current_theme_supports( 'html5', 'something-else' ) );
 	}
 
 	/**
@@ -106,19 +109,29 @@ class Tests_Theme_Support extends WP_UnitTestCase {
 		$this->assertTrue( current_theme_supports( 'html5' ) );
 
 		// It appends, rather than replaces.
-		$this->assertFalse( current_theme_supports( 'html5', 'comments-list' ) );
-		$this->assertNotSame( false, add_theme_support( 'html5', array( 'comments-list' ) ) );
+		$this->assertFalse( current_theme_supports( 'html5', 'comment-list' ) );
+		$this->assertNotSame( false, add_theme_support( 'html5', array( 'comment-list' ) ) );
 		$this->assertTrue( current_theme_supports( 'html5', 'comment-form' ) );
-		$this->assertTrue( current_theme_supports( 'html5', 'comments-list' ) );
+		$this->assertTrue( current_theme_supports( 'html5', 'comment-list' ) );
 		$this->assertFalse( current_theme_supports( 'html5', 'search-form' ) );
 
 		// Removal is all or nothing.
 		$this->assertTrue( remove_theme_support( 'html5' ) );
-		$this->assertFalse( current_theme_supports( 'html5', 'comments-list' ) );
-		$this->assertFalse( current_theme_supports( 'html5', 'comments-form' ) );
+		$this->assertFalse( current_theme_supports( 'html5', 'comment-list' ) );
+		$this->assertFalse( current_theme_supports( 'html5', 'comment-form' ) );
 		$this->assertFalse( current_theme_supports( 'html5', 'search-form' ) );
 	}
 
+	/**
+	 * @ticket 24932
+	 */
+	function test_supports_html5_invalid() {
+		remove_theme_support( 'html5' );
+		$this->assertFalse( add_theme_support( 'html5', 'comment-form' ) );
+		$this->assertFalse( current_theme_supports( 'html5', 'comment-form' ) );
+		$this->assertFalse( current_theme_supports( 'html5' ) );
+	}
+
 	function supports_foobar( $yesno, $args, $feature ) {
 		if ( $args[0] == $feature[0] )
 			return true;