diff --git a/wp-includes/post.php b/wp-includes/post.php
index 236255caad..844e3abd56 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -3338,7 +3338,7 @@ function _wp_put_post_revision( $post = null, $autosave = false ) {
 	if ( !$post || empty($post['ID']) )
 		return;
 
-	if ( isset($post['post_type']) && 'revision' == $post_post['type'] )
+	if ( isset($post['post_type']) && 'revision' == $post['post_type'] )
 		return new WP_Error( 'post_type', __( 'Cannot create a revision of a revision' ) );
 
 	$post = _wp_post_revision_fields( $post, $autosave );