Index: wp-includes/post-template.php
===================================================================
--- wp-includes/post-template.php	(revision 19896)
+++ wp-includes/post-template.php	(working copy)
@@ -370,9 +370,10 @@
 		$classes = array_merge($classes, $class);
 	}
 
-	$classes = array_map('esc_attr', $classes);
+	$classes = apply_filters( 'post_class', $classes, $class, $post->ID );
+	$classes = array_map( 'esc_attr', $classes );
 
-	return apply_filters('post_class', $classes, $class, $post->ID);
+	return $classes;
 }
 
 /**
@@ -542,9 +543,10 @@
 		$class = array();
 	}
 
+	$classes = apply_filters( 'body_class', $classes, $class );
 	$classes = array_map( 'esc_attr', $classes );
 
-	return apply_filters( 'body_class', $classes, $class );
+	return $classes;
 }
 
 /**