diff --git a/R/packages.R b/R/packages.R
index 629635b..f63a266 100644
--- a/R/packages.R
+++ b/R/packages.R
@@ -189,3 +189,12 @@ reinstall_from_cran = function(dry_run = TRUE, skip_github = TRUE) {
 }
 
 base_pkgs = function() rownames(installed.packages(priority = 'base'))
+
+# update one package (from source by default)
+pkg_update_one = function(pkg, type = 'source') {
+  opts = options(repos = c(CRAN = 'https://cran.r-project.org'))
+  on.exit(options(opts), add = TRUE)
+  if (is.null(pkgs <- old.packages(type = type)) || !pkg %in% rownames(pkgs)) return()
+  install.packages(pkg, pkgs[pkg, 'LibPath'], type = type, INSTALL_opts = '--no-staged-install')
+  NULL
+}