diff --git a/wp-includes/kses.php b/wp-includes/kses.php
index c95b0179f2..0cf4ce14c4 100644
--- a/wp-includes/kses.php
+++ b/wp-includes/kses.php
@@ -827,7 +827,8 @@ function wp_kses_attr($element, $attr, $allowed_html, $allowed_protocols) {
 		$xhtml_slash = ' /';
 
 	// Are any attributes allowed at all for this element?
-	if ( ! isset( $allowed_html[ strtolower( $element ) ] ) || true === $allowed_html[ strtolower( $element ) ] || count( $allowed_html[ strtolower( $element ) ] ) == 0 ) {
+	$element_low = strtolower( $element );
+	if ( empty( $allowed_html[ $element_low ] ) || true === $allowed_html[ $element_low ] ) {
 		return "<$element$xhtml_slash>";
 	}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 69b14a713b..31604ec633 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.5-alpha-42859';
+$wp_version = '4.9.5-alpha-42861';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.