diff --git a/src/main/kotlin/fr/dcproject/Application.kt b/src/main/kotlin/fr/dcproject/Application.kt
index eb37ef9..b15a730 100644
--- a/src/main/kotlin/fr/dcproject/Application.kt
+++ b/src/main/kotlin/fr/dcproject/Application.kt
@@ -79,7 +79,7 @@ fun Application.module(env: Env = PROD) {
             decode { values, _ ->
                 values.singleOrNull()?.let {
                     get<RepositoryArticle>().findById(UUID.fromString(it))
-                        ?: throw InternalError("Article $values not found")
+                        ?: throw NotFoundException("Article $values not found")
                 } ?: throw NotFoundException("Article $values not found")
             }
         }
@@ -91,6 +91,14 @@ fun Application.module(env: Env = PROD) {
             }
         }
 
+        convert<CommentRef> {
+            decode { values, _ ->
+                values.singleOrNull()?.let {
+                    CommentRef(UUID.fromString(it))
+                } ?: throw NotFoundException("Comment $values not found")
+            }
+        }
+
         convert<Constitution> {
             decode { values, _ ->
                 val id = values.singleOrNull()?.let { UUID.fromString(it) }
diff --git a/src/main/kotlin/fr/dcproject/entity/Comment.kt b/src/main/kotlin/fr/dcproject/entity/Comment.kt
index f53dc1a..7661790 100644
--- a/src/main/kotlin/fr/dcproject/entity/Comment.kt
+++ b/src/main/kotlin/fr/dcproject/entity/Comment.kt
@@ -1,7 +1,6 @@
 package fr.dcproject.entity
 
-import fr.postgresjson.entity.immutable.EntityUpdatedAt
-import fr.postgresjson.entity.immutable.EntityUpdatedAtImp
+import fr.postgresjson.entity.immutable.*
 import fr.postgresjson.entity.mutable.EntityDeletedAt
 import fr.postgresjson.entity.mutable.EntityDeletedAtImp
 import java.util.*
@@ -9,13 +8,16 @@ import java.util.*
 open class Comment<T : TargetI>(
     id: UUID = UUID.randomUUID(),
     override val createdBy: CitizenBasic,
-    target: T,
+    override var target: T,
     var content: String,
     val responses: List<Comment<T>>? = null,
     var parent: Comment<T>? = null,
     val parentsIds: List<UUID>? = null,
     val childrenCount: Int? = null
-) : Extra<T>(id, createdBy, target),
+) : ExtraI<T>,
+    CommentRef(id),
+    EntityCreatedAt by EntityCreatedAtImp(),
+    EntityCreatedBy<CitizenBasicI> by EntityCreatedByImp(createdBy),
     EntityUpdatedAt by EntityUpdatedAtImp(),
     EntityDeletedAt by EntityDeletedAtImp(),
     Votable by VotableImp(),
@@ -33,3 +35,7 @@ open class Comment<T : TargetI>(
 
     override val reference get() = TargetI.getReference(this)
 }
+
+open class CommentRef(id: UUID = UUID.randomUUID()) : CommentS(id)
+
+sealed class CommentS(id: UUID) : UuidEntity(id)
diff --git a/src/main/kotlin/fr/dcproject/entity/Extra.kt b/src/main/kotlin/fr/dcproject/entity/Extra.kt
index 1c69c43..5d32250 100644
--- a/src/main/kotlin/fr/dcproject/entity/Extra.kt
+++ b/src/main/kotlin/fr/dcproject/entity/Extra.kt
@@ -1,6 +1,9 @@
 package fr.dcproject.entity
 
-import fr.postgresjson.entity.immutable.*
+import fr.postgresjson.entity.immutable.EntityCreatedAt
+import fr.postgresjson.entity.immutable.EntityCreatedBy
+import fr.postgresjson.entity.immutable.UuidEntity
+import fr.postgresjson.entity.immutable.UuidEntityI
 import java.util.*
 import kotlin.reflect.KClass
 import kotlin.reflect.full.isSuperclassOf
@@ -9,19 +12,9 @@ interface ExtraI<T : TargetI> :
     UuidEntityI,
     EntityCreatedAt,
     EntityCreatedBy<CitizenBasicI> {
-    var target: T
+    val target: T
 }
 
-abstract class Extra<T : TargetI>(
-    id: UUID = UUID.randomUUID(),
-    override val createdBy: CitizenBasic,
-    override var target: T
-) :
-    ExtraI<T>,
-    UuidEntity(id),
-    EntityCreatedAt by EntityCreatedAtImp(),
-    EntityCreatedBy<CitizenBasicI> by EntityCreatedByImp(createdBy)
-
 open class TargetRef(id: UUID = UUID.randomUUID()) : TargetI, UuidEntity(id) {
     override val reference: String = ""
         get() {
diff --git a/src/main/kotlin/fr/dcproject/entity/Follow.kt b/src/main/kotlin/fr/dcproject/entity/Follow.kt
index 8b3ea4f..13eb5d5 100644
--- a/src/main/kotlin/fr/dcproject/entity/Follow.kt
+++ b/src/main/kotlin/fr/dcproject/entity/Follow.kt
@@ -1,9 +1,13 @@
 package fr.dcproject.entity
 
+import fr.postgresjson.entity.immutable.*
 import java.util.*
 
 class Follow<T : TargetI>(
     id: UUID = UUID.randomUUID(),
     override val createdBy: CitizenBasic,
-    target: T
-) : Extra<T>(id, createdBy, target)
+    override var target: T
+) : ExtraI<T>,
+    UuidEntity(id),
+    EntityCreatedAt by EntityCreatedAtImp(),
+    EntityCreatedBy<CitizenBasicI> by EntityCreatedByImp(createdBy)
diff --git a/src/main/kotlin/fr/dcproject/entity/Vote.kt b/src/main/kotlin/fr/dcproject/entity/Vote.kt
index e026cc3..e5e70ed 100644
--- a/src/main/kotlin/fr/dcproject/entity/Vote.kt
+++ b/src/main/kotlin/fr/dcproject/entity/Vote.kt
@@ -1,16 +1,18 @@
 package fr.dcproject.entity
 
-import fr.postgresjson.entity.immutable.EntityUpdatedAt
-import fr.postgresjson.entity.immutable.EntityUpdatedAtImp
+import fr.postgresjson.entity.immutable.*
 import java.util.*
 
 open class Vote<T : TargetI>(
     id: UUID = UUID.randomUUID(),
     override val createdBy: CitizenBasic,
-    target: T,
+    override var target: T,
     var note: Int,
     var anonymous: Boolean = true
-) : Extra<T>(id, createdBy, target),
+) : ExtraI<T>,
+    UuidEntity(id),
+    EntityCreatedAt by EntityCreatedAtImp(),
+    EntityCreatedBy<CitizenBasicI> by EntityCreatedByImp(createdBy),
     EntityUpdatedAt by EntityUpdatedAtImp() {
     init {
         if (note > 1 && note < -1) {
diff --git a/src/main/kotlin/fr/dcproject/routes/Comment.kt b/src/main/kotlin/fr/dcproject/routes/Comment.kt
index 3c8d246..4231711 100644
--- a/src/main/kotlin/fr/dcproject/routes/Comment.kt
+++ b/src/main/kotlin/fr/dcproject/routes/Comment.kt
@@ -2,6 +2,7 @@ package fr.dcproject.routes
 
 import fr.dcproject.citizen
 import fr.dcproject.entity.Comment
+import fr.dcproject.entity.CommentRef
 import fr.dcproject.routes.CommentPaths.CreateCommentRequest.Content
 import fr.dcproject.security.voter.CommentVoter.Action.*
 import fr.dcproject.security.voter.assertCan
@@ -19,9 +20,8 @@ import fr.dcproject.repository.CommentGeneric as CommentRepository
 
 @KtorExperimentalLocationsAPI
 object CommentPaths {
-    // TODO: change UUID by entity converter
     @Location("/comments/{comment}")
-    class CommentRequest(val comment: UUID)
+    class CommentRequest(val comment: CommentRef)
 
     @Location("/comments/{comment}/children")
     class CommentChildrenRequest(
@@ -35,7 +35,7 @@ object CommentPaths {
     }
 
     @Location("/comments/{comment}/children")
-    class CreateCommentRequest(val comment: UUID) {
+    class CreateCommentRequest(val comment: CommentRef) {
         class Content(val content: String)
     }
 }
@@ -44,7 +44,7 @@ object CommentPaths {
 @KtorExperimentalLocationsAPI
 fun Route.comment(repo: CommentRepository) {
     get<CommentPaths.CommentRequest> {
-        val comment = repo.findById(it.comment)!!
+        val comment = repo.findById(it.comment.id)!!
         assertCan(VIEW, comment)
 
         call.respond(HttpStatusCode.OK, comment)
@@ -64,7 +64,7 @@ fun Route.comment(repo: CommentRepository) {
     }
 
     post<CommentPaths.CreateCommentRequest> {
-        val parent = repo.findById(it.comment) ?: throw NotFoundException("Comment not found")
+        val parent = repo.findById(it.comment.id) ?: throw NotFoundException("Comment not found")
         val newComment = Comment(
             content = call.receive<Content>().content,
             createdBy = citizen,
@@ -78,7 +78,7 @@ fun Route.comment(repo: CommentRepository) {
     }
 
     put<CommentPaths.CommentRequest> {
-        val comment = repo.findById(it.comment)!!
+        val comment = repo.findById(it.comment.id)!!
         assertCan(UPDATE, comment)
 
         comment.content = call.receiveText()