diff --git a/wp-admin/includes/post.php b/wp-admin/includes/post.php
index 23cdfc9f7c..e4866ad516 100644
--- a/wp-admin/includes/post.php
+++ b/wp-admin/includes/post.php
@@ -235,8 +235,8 @@ function edit_post( $post_data = null ) {
 			}
 		}
 
-		if ( isset( $post_data['attachments'][ $post_ID ] ) )
-			$post_data = apply_filters( 'attachment_fields_to_save', $post_data, $post_data['attachments'][ $post_ID ] );
+		$attachment_data = isset( $post_data['attachments'][ $post_ID ] ) ? $post_data['attachments'][ $post_ID ] : array();
+		$post_data = apply_filters( 'attachment_fields_to_save', $post_data, $attachment_data );
 	}
 
 	add_meta( $post_ID );