diff -urpN gdb-6.7-orig/gdb/valops.c gdb-6.7/gdb/valops.c
--- gdb-6.7-orig/gdb/valops.c	2007-08-23 20:08:46.000000000 +0200
+++ gdb-6.7/gdb/valops.c	2008-03-03 22:05:59.000000000 +0100
@@ -623,10 +623,12 @@ value_assign (struct value *toval, struc
 	struct frame_info *frame;
 	int value_reg;
 
-	/* Figure out which frame this is in currently.  */
-	frame = frame_find_by_id (VALUE_FRAME_ID (toval));
 	value_reg = VALUE_REGNUM (toval);
+	if (value_reg < 0)
+	  error (_("Invalid register %d"), value_reg);
 
+	/* Figure out which frame this is in currently.  */
+	frame = frame_find_by_id (VALUE_FRAME_ID (toval));
 	if (!frame)
 	  error (_("Value being assigned to is no longer active."));