Index: register.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/register.el,v
retrieving revision 1.56
diff -p -u -w -r1.56 register.el
--- register.el	26 Jul 2007 05:26:32 -0000	1.56
+++ register.el	2 Nov 2007 19:00:03 -0000
@@ -287,10 +287,14 @@ With prefix arg, delete as well.
 Called from program, takes four args: REGISTER, START, END and DELETE-FLAG.
 START and END are buffer positions indicating what to append."
   (interactive "cAppend to register: \nr\nP")
-  (or (stringp (get-register register))
-      (error "Register does not contain text"))
-  (set-register register (concat (get-register register)
-			    (filter-buffer-substring start end)))
+  (let ((reg (get-register register)))
+    (cond
+     ((not reg) (set-register register (filter-buffer-substring start end)))
+     ((stringp reg)
+      (set-register register
+                    (concat reg (filter-buffer-substring start end))))
+     (t
+      (error "Register does not contain text"))))
   (if delete-flag (delete-region start end)))
 
 (defun prepend-to-register (register start end &optional delete-flag)
@@ -299,10 +303,14 @@ With prefix arg, delete as well.
 Called from program, takes four args: REGISTER, START, END and DELETE-FLAG.
 START and END are buffer positions indicating what to prepend."
   (interactive "cPrepend to register: \nr\nP")
-  (or (stringp (get-register register))
-      (error "Register does not contain text"))
-  (set-register register (concat (filter-buffer-substring start end)
-			    (get-register register)))
+  (let ((reg (get-register register)))
+    (cond
+     ((not reg) (set-register register (filter-buffer-substring start end)))
+     ((stringp reg)
+      (set-register register
+                    (concat (filter-buffer-substring start end) reg)))
+     (t
+      (error "Register does not contain text"))))
   (if delete-flag (delete-region start end)))
 
 (defun copy-rectangle-to-register (register start end &optional delete-flag)