Index: /trunk/ccl/hemlock/src/lispmode.lisp
===================================================================
--- /trunk/ccl/hemlock/src/lispmode.lisp	(revision 863)
+++ /trunk/ccl/hemlock/src/lispmode.lisp	(revision 864)
@@ -1215,4 +1215,5 @@
       (funcall (value parse-end-function) m2)
       (parse-over-block (mark-line m1) (mark-line m2)))
+    (hi::modifying-buffer (hi::line-%buffer (mark-line start))
     (let* ((first-line (mark-line start))
 	   (last-line (mark-line end))
@@ -1233,5 +1234,5 @@
 	    (setq prev-line-info line-info))
 	  (when (eq line last-line) (return nil))))
-      (make-region-undo :twiddle undo-text buf-region undo-region))))
+      (make-region-undo :twiddle undo-text buf-region undo-region)))))
 
 ;;; INDENT-FOR-LISP -- Internal.