diff -up bash-4.2/subst.c.old bash-4.2/subst.c
--- bash-4.2/subst.c.old	2015-12-09 13:24:47.369738319 +0100
+++ bash-4.2/subst.c	2015-12-09 13:28:27.366024824 +0100
@@ -2713,6 +2713,8 @@ do_compound_assignment (name, value, fla
       else if (v == 0 || (array_p (v) == 0 && assoc_p (v) == 0) || v->context != variable_context)
         v = make_local_array_variable (name);
       assign_compound_array_list (v, list, flags);
+      if (list)
+	dispose_words (list);
     }
   else
     v = assign_array_from_string (name, value, flags);