diff --git a/wp-includes/shortcodes.php b/wp-includes/shortcodes.php
index d16227ea3c..a34f530620 100644
--- a/wp-includes/shortcodes.php
+++ b/wp-includes/shortcodes.php
@@ -399,7 +399,7 @@ function do_shortcodes_in_html_tags( $content, $ignore_html ) {
 				if ( $count > 0 ) {
 					// Sanitize the shortcode output using KSES.
 					$new_attr = wp_kses_one_attr( $new_attr, $elname );
-					if ( '' !== $new_attr ) {
+					if ( '' !== trim( $new_attr ) ) {
 						// The shortcode is safe to use now.
 						$attr = $new_attr;
 					}
diff --git a/wp-includes/version.php b/wp-includes/version.php
index ea41cee8de..dcf6aa1663 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-RC2-33599';
+$wp_version = '4.3-RC2-33600';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.