diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index fe320118b0..2e77616fa0 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -374,7 +374,7 @@ function wptexturize_primes( $haystack, $needle, $prime, $open_quote, $close_quo
  */
 function _wptexturize_pushpop_element( $text, &$stack, $disabled_elements ) {
 	// Is it an opening tag or closing tag?
-	if ( '/' !== $text[1] ) {
+	if ( isset( $text[1] ) && '/' !== $text[1] ) {
 		$opening_tag = true;
 		$name_offset = 1;
 	} elseif ( 0 == count( $stack ) ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 4f69925b84..8945d4d4b0 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.5-alpha-36577';
+$wp_version = '4.5-alpha-36578';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.