Index: wp-includes/query.php
===================================================================
--- wp-includes/query.php	(revision 15621)
+++ wp-includes/query.php	(working copy)
@@ -1927,7 +1927,12 @@
 		if ( !empty( $tax_query ) ) {
 			$this->tax_query = $tax_query;
 
-			$where .= " AND $wpdb->posts.ID IN( " . implode( ', ', wp_tax_query( $tax_query ) ) . ")";
+			$tax_found_posts = wp_tax_query( $tax_query );
+
+			if ( empty( $tax_found_posts ) )
+				$where .= " AND 0 = 1";
+			else
+				$where .= " AND $wpdb->posts.ID IN( " . implode( ', ', $tax_found_posts ) . ")";
 		}
 
 		if ( !empty($q['meta_key']) ) {