diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6bd72d8e75..e7ea38cb3e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -44,6 +44,11 @@
 
 ### 0.28.3
 
+* Common`:
+    * Version updates:
+        * `Klock`: `0.12.0` -> `0.12.1`
+        * `Kotlin serialization`: `1.0.0-RC` -> `1.0.0-RC2` (dependency `kotlinx-serialization-core` was replaced with
+        `kotlinx-serialization-json` due to [kotlinx.serialization library update](https://github.com/Kotlin/kotlinx.serialization/blob/master/CHANGELOG.md#100-rc2--2020-09-21))
 * `TelegramBotAPI-core`:
     * All `InlineQueryResult` has changed their type of id for more obvious relation between `InlineQueryResult#id` and
     `ChosenInlineResult#resultId`: `String` -> `InlineQueryIdentifier`
diff --git a/TelegramBotAPI-core/build.gradle b/TelegramBotAPI-core/build.gradle
index 19420bf448..eaf93b61f8 100644
--- a/TelegramBotAPI-core/build.gradle
+++ b/TelegramBotAPI-core/build.gradle
@@ -41,7 +41,7 @@ kotlin {
             dependencies {
                 implementation kotlin('stdlib')
                 api "org.jetbrains.kotlinx:kotlinx-coroutines-core:$kotlin_coroutines_version"
-                api "org.jetbrains.kotlinx:kotlinx-serialization-core:$kotlin_serialisation_runtime_version"
+                api "org.jetbrains.kotlinx:kotlinx-serialization-json:$kotlin_serialisation_runtime_version"
                 api "org.jetbrains.kotlinx:kotlinx-serialization-properties:$kotlin_serialisation_runtime_version"
 
                 api "com.soywiz.korlibs.klock:klock:$klock_version"
diff --git a/TelegramBotAPI-core/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/JSON.kt b/TelegramBotAPI-core/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/JSON.kt
index 01c3d0f8b5..1a4e506d12 100644
--- a/TelegramBotAPI-core/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/JSON.kt
+++ b/TelegramBotAPI-core/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/JSON.kt
@@ -8,6 +8,7 @@ internal val nonstrictJsonFormat = Json {
     ignoreUnknownKeys = true
     allowSpecialFloatingPointValues = true
     useArrayPolymorphism = true
+    encodeDefaults = true
 }
 
 fun <T: Any> T.toJsonWithoutNulls(serializer: SerializationStrategy<T>): JsonObject = toJson(serializer).withoutNulls()
diff --git a/TelegramBotAPI-core/src/commonTest/kotlin/com/github/insanusmokrassar/TelegramBotAPI/SimpleInputFilesTest.kt b/TelegramBotAPI-core/src/commonTest/kotlin/com/github/insanusmokrassar/TelegramBotAPI/SimpleInputFilesTest.kt
index 1da2a34a55..22294176ea 100644
--- a/TelegramBotAPI-core/src/commonTest/kotlin/com/github/insanusmokrassar/TelegramBotAPI/SimpleInputFilesTest.kt
+++ b/TelegramBotAPI-core/src/commonTest/kotlin/com/github/insanusmokrassar/TelegramBotAPI/SimpleInputFilesTest.kt
@@ -13,6 +13,7 @@ private val nonstrictJsonFormat = Json {
     ignoreUnknownKeys = true
     allowSpecialFloatingPointValues = true
     useArrayPolymorphism = true
+    encodeDefaults = true
 }
 
 class SimpleInputFilesTest {
diff --git a/TelegramBotAPI-core/src/commonTest/kotlin/com/github/insanusmokrassar/TelegramBotAPI/TestsJsonFormat.kt b/TelegramBotAPI-core/src/commonTest/kotlin/com/github/insanusmokrassar/TelegramBotAPI/TestsJsonFormat.kt
index c027bfd689..913df02bde 100644
--- a/TelegramBotAPI-core/src/commonTest/kotlin/com/github/insanusmokrassar/TelegramBotAPI/TestsJsonFormat.kt
+++ b/TelegramBotAPI-core/src/commonTest/kotlin/com/github/insanusmokrassar/TelegramBotAPI/TestsJsonFormat.kt
@@ -2,4 +2,6 @@ package com.github.insanusmokrassar.TelegramBotAPI
 
 import kotlinx.serialization.json.Json
 
-val TestsJsonFormat = Json {}
+val TestsJsonFormat = Json {
+    encodeDefaults = true
+}
diff --git a/TelegramBotAPI-extensions-api/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/extensions/api/JsonUtils.kt b/TelegramBotAPI-extensions-api/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/extensions/api/JsonUtils.kt
index 0a4153f2c1..2ae50a6cdb 100644
--- a/TelegramBotAPI-extensions-api/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/extensions/api/JsonUtils.kt
+++ b/TelegramBotAPI-extensions-api/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/extensions/api/JsonUtils.kt
@@ -8,4 +8,5 @@ internal val nonstrictJsonFormat = Json {
     ignoreUnknownKeys = true
     allowSpecialFloatingPointValues = true
     useArrayPolymorphism = true
+    encodeDefaults = true
 }
diff --git a/TelegramBotAPI-extensions-utils/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/extensions/utils/JsonFormat.kt b/TelegramBotAPI-extensions-utils/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/extensions/utils/JsonFormat.kt
index 86b3f21720..76b4a1d614 100644
--- a/TelegramBotAPI-extensions-utils/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/extensions/utils/JsonFormat.kt
+++ b/TelegramBotAPI-extensions-utils/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/extensions/utils/JsonFormat.kt
@@ -8,4 +8,5 @@ internal val nonstrictJsonFormat = Json {
     ignoreUnknownKeys = true
     allowSpecialFloatingPointValues = true
     useArrayPolymorphism = true
+    encodeDefaults = true
 }
diff --git a/gradle.properties b/gradle.properties
index 89d3e9ce4e..f6c24eaf52 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -7,8 +7,8 @@ kotlin.incremental.js=true
 
 kotlin_version=1.4.10
 kotlin_coroutines_version=1.3.9
-kotlin_serialisation_runtime_version=1.0.0-RC
-klock_version=1.12.0
+kotlin_serialisation_runtime_version=1.0.0-RC2
+klock_version=1.12.1
 uuid_version=0.2.2
 ktor_version=1.4.0