diff --git a/wp-includes/class-wp-comment-query.php b/wp-includes/class-wp-comment-query.php
index 1068050d38..eb6f094a5e 100644
--- a/wp-includes/class-wp-comment-query.php
+++ b/wp-includes/class-wp-comment-query.php
@@ -745,7 +745,8 @@ class WP_Comment_Query {
 			$this->sql_clauses['where']['user_id'] = $wpdb->prepare( 'user_id = %d', $this->query_vars['user_id'] );
 		}
 
-		if ( '' !== $this->query_vars['search'] ) {
+		// Falsy search strings are ignored.
+		if ( strlen( $this->query_vars['search'] ) ) {
 			$search_sql = $this->get_search_sql(
 				$this->query_vars['search'],
 				array( 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_author_IP', 'comment_content' )
diff --git a/wp-includes/version.php b/wp-includes/version.php
index fb08a34b14..a52a6c6e0a 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.5-alpha-1453147032750';
+$wp_version = '4.5-alpha-1453172113095';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.