diff --git a/lib/index.js b/lib/index.js
index 2f8f5d3b1..343e179de 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -135,6 +135,15 @@ module.exports = function(config_hash) {
 	// publishing a package
 	app.put('/:package', can('publish'), media('application/json'), expect_json, function(req, res, next) {
 		var name = req.params.package;
+
+		if (Object.keys(req.body).length == 1 && typeof(req.body.users) === 'object') {
+			return next(new UError({
+				// 501 status is more meaningful, but npm doesn't show error message for 5xx
+				status: 404,
+				msg: 'npm star|unstar calls are not implemented',
+			}));
+		}
+
 		try {
 			var metadata = utils.validate_metadata(req.body, name);
 		} catch(err) {