diff --git a/lib/configure-map.js b/lib/configure-map.js
index 2d2e55f..dafe8cf 100644
--- a/lib/configure-map.js
+++ b/lib/configure-map.js
@@ -145,6 +145,7 @@ module.exports = function (original, length, options) {
 		var id, args = arguments;
 		if (resolve) args = resolve(args);
 		id = get(args);
+		if (id === null) return false;
 		return conf.has(id);
 	});
 	defineProperties(memoized, {