diff --git a/wp-includes/query.php b/wp-includes/query.php
index 756e5e5c52..09c507b47e 100644
--- a/wp-includes/query.php
+++ b/wp-includes/query.php
@@ -1947,8 +1947,12 @@ class WP_Query {
 		if ( !empty( $this->tax_query ) ) {
 			$clauses = call_user_func_array( 'get_tax_sql', array( $this->tax_query, $wpdb->posts, 'ID', &$this) );
 
-			$join .= $clauses['join'];
-			$where .= $clauses['where'];
+			if ( empty($clauses['join']) && empty($clauses['where']) ) {
+				$where .= ' AND 0 = 1';	
+			} else {
+				$join .= $clauses['join'];
+				$where .= $clauses['where'];
+			}
 
 			if ( $this->is_tax ) {
 				if ( empty($post_type) ) {
diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index 8135cdddda..977e9bf16f 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -539,7 +539,7 @@ function get_tax_sql( $tax_query, $primary_table, $primary_id_column ) {
 
 		foreach ( $taxonomies as $taxonomy ) {
 			if ( ! taxonomy_exists( $taxonomy ) )
-				return ' AND 0 = 1';
+				return array( 'join' => '', 'where' => ' AND 0 = 1');
 		}
 
 		$taxonomies = "'" . implode( "', '", $taxonomies ) . "'";
@@ -592,6 +592,7 @@ function get_tax_sql( $tax_query, $primary_table, $primary_id_column ) {
 			)";
 		}
 	}
+
 	return compact( 'join', 'where' );
 }