diff --git a/package-lock.json b/package-lock.json
index 245790d..75afd8e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -226,8 +226,8 @@
             "integrity": "sha1-dWnKqKo/jVk11i4fqW+fcCzYHHk=",
             "dev": true,
             "requires": {
-                "acorn": "3.3.0",
-                "is-expression": "2.1.0"
+                "acorn": "^3.1.0",
+                "is-expression": "^2.0.1"
             }
         },
         "core-util-is": {