diff --git a/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/numeral/Predicates.scala b/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/numeral/Predicates.scala
index 9e17178..5879035 100644
--- a/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/numeral/Predicates.scala
+++ b/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/numeral/Predicates.scala
@@ -63,6 +63,12 @@ object Predicates {
     case _ => false
   }
 
+  val isNonNegative: Predicate = {
+    case Token(Numeral, NumeralData(v, _, _, _, _, precision)) => precision == 0 && isInteger(v) && v >= 0
+    case Token(UnitNumber, NumeralData(v, _, _, _, _, precision)) => precision == 0 && isInteger(v) && v >= 0
+    case _ => false
+  }
+
   val isInteger: Predicate = {
     case Token(_, NumeralData(v, _, _, _, _, precision)) => precision == 0 && isInteger(v)
   }
diff --git a/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/time/duration/Rules.scala b/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/time/duration/Rules.scala
index 9d44c9f..80fd0a7 100644
--- a/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/time/duration/Rules.scala
+++ b/duckling-fork-chinese/core/src/main/scala/com/xiaomi/duckling/dimension/time/duration/Rules.scala
@@ -53,7 +53,7 @@ trait Rules extends DimRules {
               val n = math.floor(v).toInt
               // 2012年 不召回, 两千年召回
               if (seq.nonEmpty && g == Year && 1950 <= n && n <= 2050) None
-              else Token(Duration, DurationData(n, g, latent = latent, schema = durationSchema(n.toString, g)))
+              else Token(Duration, DurationData(n, g, latent = if (v == 0) true else latent, schema = durationSchema(n.toString, g)))
             case _ => None
           }
         }
@@ -64,7 +64,7 @@ trait Rules extends DimRules {
     name = "<integer> <unit-of-duration>",
     pattern = List(
       and(
-        isNatural,
+        isNonNegative,
         isNumberOrUnitNumber,
         not(isDigitLengthGt(1)),
         // 一九八七 年 不召回