diff --git a/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/time/date/Rules.scala b/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/time/date/Rules.scala
index 17638ed..8eca993 100644
--- a/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/time/date/Rules.scala
+++ b/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/time/date/Rules.scala
@@ -410,7 +410,7 @@ trait Rules extends DimRules {
     prod = regexMatch {case text :: _ =>
       val m = WeekX.matcher(text)
       var pos = 0
-      val days = mutable.MutableList[Int]()
+      val days = mutable.Buffer[Int]()
       while (m.find(pos)) {
         val d = m.group(2) match {
           case "一" => 1