#include "cache.h"
 #include "commit.h"
 #include "color.h"
+#include "utf8.h"
 
 static int parse_options_usage(struct parse_opt_ctx_t *ctx,
                               const char * const *usagestr,
        default: /* PARSE_OPT_UNKNOWN */
                if (ctx.argv[0][1] == '-') {
                        error("unknown option `%s'", ctx.argv[0] + 2);
-               } else {
+               } else if (isascii(*ctx.opt)) {
                        error("unknown switch `%c'", *ctx.opt);
+               } else {
+                       error("unknown non-ascii option in string: `%s'",
+                             ctx.argv[0]);
                }
                usage_with_options(usagestr, options);
        }
                        s = literal ? "[%s]" : "[<%s>]";
        else
                s = literal ? " %s" : " <%s>";
-       return fprintf(outfile, s, opts->argh ? _(opts->argh) : _("..."));
+       return utf8_fprintf(outfile, s, opts->argh ? _(opts->argh) : _("..."));
 }
 
 #define USAGE_OPTS_WIDTH 24
                if (opts->long_name)
                        pos += fprintf(outfile, "--%s", opts->long_name);
                if (opts->type == OPTION_NUMBER)
-                       pos += fprintf(outfile, "-NUM");
+                       pos += utf8_fprintf(outfile, _("-NUM"));
 
                if ((opts->flags & PARSE_OPT_LITERAL_ARGHELP) ||
                    !(opts->flags & PARSE_OPT_NOARG))