diff --git a/buildSrc/src/main/kotlin/Libs.kt b/buildSrc/src/main/kotlin/Libs.kt
index 362872b6e9..0765627f26 100644
--- a/buildSrc/src/main/kotlin/Libs.kt
+++ b/buildSrc/src/main/kotlin/Libs.kt
@@ -12,7 +12,7 @@ object Versions {
     const val grgit = "4.1.1"
     const val detekt = "1.22.0"
     const val dokka = "1.7.20"
-    const val mkdocs = "3.0.0"
+    const val mkdocs = "4.0.1"
     // With 0.13.0 ':integ-tests:transformJvmTestAtomicfu' task somehow fails
     const val binaryCompatibilityValidator = "0.12.1"
 
diff --git a/elasticmagic-transport-ktor/api/elasticmagic-transport-ktor.api b/elasticmagic-transport-ktor/api/elasticmagic-transport-ktor.api
index fc2230da24..b6fcbd0c53 100644
--- a/elasticmagic-transport-ktor/api/elasticmagic-transport-ktor.api
+++ b/elasticmagic-transport-ktor/api/elasticmagic-transport-ktor.api
@@ -1,5 +1,5 @@
 public final class dev/evo/elasticmagic/transport/ElasticsearchKtorTransport : dev/evo/elasticmagic/transport/ElasticsearchTransport {
-	public fun <init> (Ljava/lang/String;Lio/ktor/client/engine/HttpClientEngine;Lkotlin/jvm/functions/Function1;)V
-	public synthetic fun <init> (Ljava/lang/String;Lio/ktor/client/engine/HttpClientEngine;Lkotlin/jvm/functions/Function1;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public fun <init> (Ljava/lang/String;Lio/ktor/client/engine/HttpClientEngine;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)V
+	public synthetic fun <init> (Ljava/lang/String;Lio/ktor/client/engine/HttpClientEngine;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 }
 
diff --git a/elasticmagic-transport-ktor/src/commonMain/kotlin/dev/evo/elasticmagic/transport/ElasticsearchKtorTransport.kt b/elasticmagic-transport-ktor/src/commonMain/kotlin/dev/evo/elasticmagic/transport/ElasticsearchKtorTransport.kt
index ca9012170a..442ebd5851 100644
--- a/elasticmagic-transport-ktor/src/commonMain/kotlin/dev/evo/elasticmagic/transport/ElasticsearchKtorTransport.kt
+++ b/elasticmagic-transport-ktor/src/commonMain/kotlin/dev/evo/elasticmagic/transport/ElasticsearchKtorTransport.kt
@@ -1,6 +1,7 @@
 package dev.evo.elasticmagic.transport
 
 import io.ktor.client.HttpClient
+import io.ktor.client.HttpClientConfig
 import io.ktor.client.engine.HttpClientEngine
 import io.ktor.client.plugins.auth.Auth
 import io.ktor.client.plugins.auth.providers.basic
@@ -21,6 +22,7 @@ import io.ktor.http.takeFrom
 class ElasticsearchKtorTransport(
     baseUrl: String,
     engine: HttpClientEngine,
+    private val customHttpClientConfig: HttpClientConfig<*>.() -> Unit = {},
     configure: Config.() -> Unit = {},
 ) : ElasticsearchTransport(
     baseUrl,
@@ -29,6 +31,8 @@ class ElasticsearchKtorTransport(
     private val client = HttpClient(engine) {
         expectSuccess = false
 
+        customHttpClientConfig(this)
+
         // Enable compressed response from Elasticsearch
         if (config.gzipRequests) {
             install(ContentEncoding) {