diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 26ac87013b..fc9b264d56 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -1319,6 +1319,7 @@ int main(int argc, char *argv[])
     if (opts.show_help) {
         printf("usage: %s [options]\n\n", argv[0]);
         fuse_cmdline_help();
+        printf("    -o source=PATH             shared directory tree\n");
         fuse_lowlevel_help();
         ret = 0;
         goto err_out1;