diff --git a/lib/core.js b/lib/core.js
index 6fc5d176..86e3fce0 100644
--- a/lib/core.js
+++ b/lib/core.js
@@ -23,7 +23,7 @@ Volcanos("core", {
 				}
 			}
 		}
-		var node = data, keys = key.split(nfs.PT); while (node && keys.length > 0) {
+		var node = data, keys = key.split(nfs.PT); while (node && keys.length > 0) { if (typeof node == "string") { return }
 			if (keys[0] == "-1") { keys[0] = node.length-1 } node = node[keys[0]], keys = keys.slice(1)
 		} return node == undefined? data[key]: node
 	},