diff --git a/build.sbt b/build.sbt
index 053b74a..5f4018d 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,7 +1,7 @@
 import scala.xml.NodeSeq
 
 val commonSettings = Seq(
-  version := "5.0",
+  version := "5.1",
   organization := "jp.t2v",
   scalaVersion := "2.12.1",
   crossScalaVersions := Seq("2.12.1"),
diff --git a/core/src/main/scala/jp/t2v/util/locale/LocalDateConverter.scala b/core/src/main/scala/jp/t2v/util/locale/LocalDateConverter.scala
index bb78db2..05266c8 100644
--- a/core/src/main/scala/jp/t2v/util/locale/LocalDateConverter.scala
+++ b/core/src/main/scala/jp/t2v/util/locale/LocalDateConverter.scala
@@ -8,8 +8,8 @@ abstract class LocalDateConverter[A] {
 }
 object LocalDateConverter extends LowPriorityLocalDateConverter {
   implicit val localDate: LocalDateConverter[LocalDate] = d => d
-  implicit def localDateTime: LocalDateConverter[LocalDateTime] = _.toLocalDate
-  implicit def zonedDateTime: LocalDateConverter[ZonedDateTime] = _.toLocalDate
+  implicit val localDateTime: LocalDateConverter[LocalDateTime] = _.toLocalDate
+  implicit val zonedDateTime: LocalDateConverter[ZonedDateTime] = _.toLocalDate
 }
 
 trait LowPriorityLocalDateConverter {