diff --git a/wp-includes/post-template.php b/wp-includes/post-template.php
index 1c98e49ede..3b491a1ace 100644
--- a/wp-includes/post-template.php
+++ b/wp-includes/post-template.php
@@ -1275,6 +1275,11 @@ function wp_page_menu( $args = array() ) {
 
 	$container = sanitize_text_field( $args['container'] );
 
+	// Fallback in case `wp_nav_menu()` was called without a container.
+	if ( empty( $container ) ) {
+		$container = 'div';
+	}
+
 	if ( $menu ) {
 
 		// wp_nav_menu doesn't set before and after
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 42e9682922..4ef2d6e7f1 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-34949';
+$wp_version = '4.4-alpha-34950';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.