Index: wp-includes/general-template.php
===================================================================
--- wp-includes/general-template.php	(revision 18515)
+++ wp-includes/general-template.php	(working copy)
@@ -1646,14 +1646,10 @@
 			$title = esc_attr(sprintf( $args['singletitle'], get_bloginfo('name'), $args['separator'], esc_html( get_the_title() ) ));
 			$href = get_post_comments_feed_link( $post->ID );
 		}
-	} elseif ( is_category() ) {
-		$term = get_queried_object();
-
+	} elseif ( is_category() && $term = get_queried_object() ) {
 		$title = esc_attr(sprintf( $args['cattitle'], get_bloginfo('name'), $args['separator'], $term->name ));
 		$href = get_category_feed_link( $term->term_id );
-	} elseif ( is_tag() ) {
-		$term = get_queried_object();
-
+	} elseif ( is_tag() && $term = get_queried_object() ) {
 		$title = esc_attr(sprintf( $args['tagtitle'], get_bloginfo('name'), $args['separator'], $term->name ));
 		$href = get_tag_feed_link( $term->term_id );
 	} elseif ( is_author() ) {
Index: wp-includes/post-template.php
===================================================================
--- wp-includes/post-template.php	(revision 18515)
+++ wp-includes/post-template.php	(working copy)
@@ -449,23 +449,19 @@
 		if ( is_post_type_archive() ) {
 			$classes[] = 'post-type-archive';
 			$classes[] = 'post-type-archive-' . sanitize_html_class( get_query_var( 'post_type' ) );
-		} else if ( is_author() ) {
-			$author = $wp_query->get_queried_object();
+		} else if ( is_author() && $author = $wp_query->get_queried_object() ) {
 			$classes[] = 'author';
 			$classes[] = 'author-' . sanitize_html_class( $author->user_nicename , $author->ID );
 			$classes[] = 'author-' . $author->ID;
-		} elseif ( is_category() ) {
-			$cat = $wp_query->get_queried_object();
+		} elseif ( is_category() && $cat = $wp_query->get_queried_object() ) {
 			$classes[] = 'category';
 			$classes[] = 'category-' . sanitize_html_class( $cat->slug, $cat->term_id );
 			$classes[] = 'category-' . $cat->term_id;
-		} elseif ( is_tag() ) {
-			$tags = $wp_query->get_queried_object();
+		} elseif ( is_tag() && $tags = $wp_query->get_queried_object() ) {
 			$classes[] = 'tag';
 			$classes[] = 'tag-' . sanitize_html_class( $tags->slug, $tags->term_id );
 			$classes[] = 'tag-' . $tags->term_id;
-		} elseif ( is_tax() ) {
-			$term = $wp_query->get_queried_object();
+		} elseif ( is_tax() && $term = $wp_query->get_queried_object() ) {
 			$classes[] = 'tax-' . sanitize_html_class( $term->taxonomy );
 			$classes[] = 'term-' . sanitize_html_class( $term->slug, $term->term_id );
 			$classes[] = 'term-' . $term->term_id;