diff --git a/src/main/scala/net/yoshinorin/qualtet/domains/authors/models/AuthorReadModel.scala b/src/main/scala/net/yoshinorin/qualtet/domains/authors/models/AuthorReadModel.scala
index a9cef841..05edba6a 100644
--- a/src/main/scala/net/yoshinorin/qualtet/domains/authors/models/AuthorReadModel.scala
+++ b/src/main/scala/net/yoshinorin/qualtet/domains/authors/models/AuthorReadModel.scala
@@ -1,18 +1,16 @@
 package net.yoshinorin.qualtet.domains.authors
 
-import java.time.ZonedDateTime
-
 final case class AuthorReadModel(
-  id: AuthorId = AuthorId.apply(),
+  id: AuthorId,
   name: AuthorName,
   displayName: AuthorDisplayName,
   password: BCryptPassword,
-  createdAt: Long = ZonedDateTime.now.toEpochSecond
+  createdAt: Long
 )
 
 final case class AuthorWithoutPasswordReadModel(
-  id: AuthorId = AuthorId.apply(),
+  id: AuthorId,
   name: AuthorName,
   displayName: AuthorDisplayName,
-  createdAt: Long = ZonedDateTime.now.toEpochSecond
+  createdAt: Long
 )
diff --git a/src/main/scala/net/yoshinorin/qualtet/domains/contentTypes/models/ContentTypeReadModel.scala b/src/main/scala/net/yoshinorin/qualtet/domains/contentTypes/models/ContentTypeReadModel.scala
index 60ecaebf..8fbd538c 100644
--- a/src/main/scala/net/yoshinorin/qualtet/domains/contentTypes/models/ContentTypeReadModel.scala
+++ b/src/main/scala/net/yoshinorin/qualtet/domains/contentTypes/models/ContentTypeReadModel.scala
@@ -1,6 +1,6 @@
 package net.yoshinorin.qualtet.domains.contentTypes
 
 final case class ContentTypeReadModel(
-  id: ContentTypeId = ContentTypeId.apply(),
+  id: ContentTypeId,
   name: String
 )
diff --git a/src/main/scala/net/yoshinorin/qualtet/domains/contents/models/ContentReadModel.scala b/src/main/scala/net/yoshinorin/qualtet/domains/contents/models/ContentReadModel.scala
index c7e3afca..d6f55b73 100644
--- a/src/main/scala/net/yoshinorin/qualtet/domains/contents/models/ContentReadModel.scala
+++ b/src/main/scala/net/yoshinorin/qualtet/domains/contents/models/ContentReadModel.scala
@@ -19,7 +19,7 @@ final case class ContentWithMetaReadModel(
 )
 
 final case class ContentReadModel(
-  id: ContentId = ContentId.apply(),
+  id: ContentId,
   authorId: AuthorId,
   contentTypeId: ContentTypeId,
   path: Path,