diff --git a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/Content.kt b/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/Content.kt
index c21ffb42..55f08b41 100644
--- a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/Content.kt
+++ b/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/Content.kt
@@ -1,17 +1,30 @@
 package com.insanusmokrassar.postssystem.core.content
 
+import kotlinx.serialization.Serializable
+
 typealias ContentId = String
 
 /**
  * Content which is planned to be registered in database
  */
-interface Content
+sealed class Content
+
+@Serializable
+data class SimpleSpecialContent(
+    val internalId: ContentId
+) : Content()
+
+@Serializable
+data class SimpleTextContent(
+    val text: String
+) : Content()
 
 /**
  * Content which is already registered in database. Using its [id] you can retrieve all known
  * [com.insanusmokrassar.postssystem.core.post.RegisteredPost]s by using
  * [com.insanusmokrassar.postssystem.core.post.api.ReadPostsAPI.getPostsByContent]
  */
-interface RegisteredContent : Content {
-    val id: ContentId
-}
+data class RegisteredContent(
+    val id: ContentId,
+    val content: Content
+)
diff --git a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/SpecialContent.kt b/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/SpecialContent.kt
deleted file mode 100644
index f4100390..00000000
--- a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/SpecialContent.kt
+++ /dev/null
@@ -1,31 +0,0 @@
-package com.insanusmokrassar.postssystem.core.content
-
-import kotlinx.serialization.Serializable
-
-/**
- * Special content, which usually better known in some plugin or system, but is not representable in others. For
- * example, it could be issue in some git system, which is unknown for all other systems.
- *
- * @property internalId Represent Id of this content in system which knows exact type and can correctly handle this
- * content
- */
-interface SpecialContent : Content {
-    val internalId: ContentId
-}
-
-/**
- * As [SpecialContent], but already registered in posts system
- */
-interface SpecialRegisteredContent : RegisteredContent, SpecialContent
-
-@Serializable
-data class SimpleSpecialContent(
-    override val internalId: ContentId
-) : SpecialContent
-
-@Serializable
-data class SimpleSpecialRegisteredContent(
-    override val id: ContentId,
-    override val internalId: ContentId
-) : SpecialRegisteredContent
-
diff --git a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/TextContent.kt b/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/TextContent.kt
deleted file mode 100644
index af2608e6..00000000
--- a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/TextContent.kt
+++ /dev/null
@@ -1,20 +0,0 @@
-package com.insanusmokrassar.postssystem.core.content
-
-import kotlinx.serialization.Serializable
-
-interface TextContent : Content {
-    val text: String
-}
-
-interface TextRegisteredContent : RegisteredContent, TextContent
-
-@Serializable
-data class SimpleTextContent(
-    override val text: String
-) : TextContent
-
-@Serializable
-data class SimpleTextRegisteredContent(
-    override val id: ContentId,
-    override val text: String
-) : TextRegisteredContent
diff --git a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/utils/IdUtils.kt b/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/utils/IdUtils.kt
new file mode 100644
index 00000000..8abc485c
--- /dev/null
+++ b/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/utils/IdUtils.kt
@@ -0,0 +1,2 @@
+package com.insanusmokrassar.postssystem.core.utils
+
diff --git a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/utils/pagination/PaginationResult.kt b/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/utils/pagination/PaginationResult.kt
index 9808f22d..b7b5e783 100644
--- a/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/utils/pagination/PaginationResult.kt
+++ b/core/src/main/kotlin/com/insanusmokrassar/postssystem/core/utils/pagination/PaginationResult.kt
@@ -2,7 +2,6 @@ package com.insanusmokrassar.postssystem.core.utils.pagination
 
 import kotlinx.serialization.Serializable
 
-@Serializable
 data class PaginationResult<T>(
     override val page: Int,
     val pagesNumber: Int,
diff --git a/core/src/test/kotlin/com/insanusmokrassar/postssystem/core/api/InMemoryContentAPI.kt b/core/src/test/kotlin/com/insanusmokrassar/postssystem/core/api/InMemoryContentAPI.kt
index 00c101dc..ed0fd2e2 100644
--- a/core/src/test/kotlin/com/insanusmokrassar/postssystem/core/api/InMemoryContentAPI.kt
+++ b/core/src/test/kotlin/com/insanusmokrassar/postssystem/core/api/InMemoryContentAPI.kt
@@ -31,7 +31,10 @@ class InMemoryContentAPI(
         .toMutableMap()
 
     override suspend fun createContent(content: Content): RegisteredContent? {
-        return content.createRegisteredEntity(generateId())?.also { registeredContent ->
+        return RegisteredContent(
+            generateId(),
+            content
+        ).also { registeredContent ->
             contents[registeredContent.id] = registeredContent
             contentCreatedBroadcastChannel.send(registeredContent)
         }
@@ -51,12 +54,4 @@ class InMemoryContentAPI(
             contentDeletedBroadcastChannel.send(content)
         } != null
     }
-
-    private fun Content.createRegisteredEntity(id: ContentId): RegisteredContent? {
-        return when(this) {
-            is TextContent -> SimpleTextRegisteredContent(id, text)
-            is SpecialContent -> SimpleTextRegisteredContent(id, internalId)
-            else -> null
-        }
-    }
 }
\ No newline at end of file