diff --git a/util/shape-options.hh b/util/shape-options.hh
index 92d273174..89dd8dfc9 100644
--- a/util/shape-options.hh
+++ b/util/shape-options.hh
@@ -421,7 +421,7 @@ shape_options_t::add_options (option_parser_t *parser)
 			      G_OPTION_ARG_CALLBACK,	(gpointer) &parse_shapers,	"Hidden duplicate of --shapers",	nullptr},
     {"shapers",		0, 0, G_OPTION_ARG_CALLBACK,	(gpointer) &parse_shapers,	"Set comma-separated list of shapers to try","list"},
     {"direction",	0, 0, G_OPTION_ARG_STRING,	&this->direction,		"Set text direction (default: auto)",	"ltr/rtl/ttb/btt"},
-    {"language",	0, 0, G_OPTION_ARG_STRING,	&this->language,		"Set text language (default: $LANG)",	"langstr"},
+    {"language",	0, 0, G_OPTION_ARG_STRING,	&this->language,		"Set text language (default: $LANG)",	"BCP 47 tag"},
     {"script",		0, 0, G_OPTION_ARG_STRING,	&this->script,			"Set text script (default: auto)",	"ISO-15924 tag"},
     {"bot",		0, 0, G_OPTION_ARG_NONE,	&this->bot,			"Treat text as beginning-of-paragraph",	nullptr},
     {"eot",		0, 0, G_OPTION_ARG_NONE,	&this->eot,			"Treat text as end-of-paragraph",	nullptr},