* Copyright (C) Junio C Hamano, 2005
  */
 #include "builtin.h"
+#include "config.h"
 #include "blob.h"
 #include "quote.h"
 #include "parse-options.h"
                OPT_END()
        };
        int i;
-       int prefix_length = -1;
        const char *errstr = NULL;
 
        argc = parse_options(argc, argv, NULL, hash_object_options,
        else
                prefix = setup_git_directory_gently(&nongit);
 
-       prefix_length = prefix ? strlen(prefix) : 0;
        if (vpath && prefix)
-               vpath = prefix_filename(prefix, prefix_length, vpath);
+               vpath = xstrdup(prefix_filename(prefix, vpath));
 
        git_config(git_default_config, NULL);
 
 
        for (i = 0 ; i < argc; i++) {
                const char *arg = argv[i];
+               char *to_free = NULL;
 
-               if (0 <= prefix_length)
-                       arg = prefix_filename(prefix, prefix_length, arg);
+               if (prefix)
+                       arg = to_free = prefix_filename(prefix, arg);
                hash_object(arg, type, no_filters ? NULL : vpath ? vpath : arg,
                            flags, literally);
+               free(to_free);
        }
 
        if (stdin_paths)