diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index 2eecfecf7c..b8261dfeec 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -832,7 +832,7 @@ class WP_Tax_Query {
 	 * @return bool  Whether the query clause is a first-order clause.
 	 */
 	protected static function is_first_order_clause( $query ) {
-		return empty( $query ) || array_key_exists( 'terms', $query ) || array_key_exists( 'taxonomy', $query ) || array_key_exists( 'include_children', $query ) || array_key_exists( 'field', $query ) || array_key_exists( 'operator', $query );
+		return is_array( $query ) && ( empty( $query ) || array_key_exists( 'terms', $query ) || array_key_exists( 'taxonomy', $query ) || array_key_exists( 'include_children', $query ) || array_key_exists( 'field', $query ) || array_key_exists( 'operator', $query ) );
 	}
 
 	/**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 30d739aa30..c6d52ea62e 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.1-alpha-30030';
+$wp_version = '4.1-alpha-30031';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.