diff --git a/ktor-client/ktor-client-core/common/src/io/ktor/client/HttpClient.kt b/ktor-client/ktor-client-core/common/src/io/ktor/client/HttpClient.kt
index 043f80d781c..9b7c3c8b373 100644
--- a/ktor-client/ktor-client-core/common/src/io/ktor/client/HttpClient.kt
+++ b/ktor-client/ktor-client-core/common/src/io/ktor/client/HttpClient.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.client
 
@@ -225,7 +225,7 @@ public class HttpClient(
             @Suppress("UNCHECKED_CAST")
             val plugin = installedFeatures[key as AttributeKey<Any>]
 
-            if (plugin is Closeable) {
+            if (plugin is AutoCloseable) {
                 plugin.close()
             }
         }
diff --git a/ktor-client/ktor-client-core/common/src/io/ktor/client/engine/HttpClientEngineBase.kt b/ktor-client/ktor-client-core/common/src/io/ktor/client/engine/HttpClientEngineBase.kt
index 0ac6ebc76fb..8c7ec428928 100644
--- a/ktor-client/ktor-client-core/common/src/io/ktor/client/engine/HttpClientEngineBase.kt
+++ b/ktor-client/ktor-client-core/common/src/io/ktor/client/engine/HttpClientEngineBase.kt
@@ -1,11 +1,10 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.client.engine
 
 import io.ktor.util.*
-import io.ktor.utils.io.core.*
 import kotlinx.atomicfu.*
 import kotlinx.coroutines.*
 import kotlin.coroutines.*
@@ -39,19 +38,4 @@ public abstract class HttpClientEngineBase(private val engineName: String) : Htt
 public class ClientEngineClosedException(override val cause: Throwable? = null) :
     IllegalStateException("Client already closed")
 
-/**
- * Closes [CoroutineDispatcher] if it's [CloseableCoroutineDispatcher] or [Closeable].
- */
-@OptIn(ExperimentalCoroutinesApi::class)
-private fun CoroutineDispatcher.close() {
-    try {
-        when (this) {
-            is CloseableCoroutineDispatcher -> close()
-            is Closeable -> close()
-        }
-    } catch (ignore: Throwable) {
-        // Some closeable dispatchers like Dispatchers.IO can't be closed.
-    }
-}
-
 internal expect fun ioDispatcher(): CoroutineDispatcher
diff --git a/ktor-server/ktor-server-core/common/src/io/ktor/server/application/ApplicationPlugin.kt b/ktor-server/ktor-server-core/common/src/io/ktor/server/application/ApplicationPlugin.kt
index f38ce7ea430..6f8012d4664 100644
--- a/ktor-server/ktor-server-core/common/src/io/ktor/server/application/ApplicationPlugin.kt
+++ b/ktor-server/ktor-server-core/common/src/io/ktor/server/application/ApplicationPlugin.kt
@@ -1,6 +1,6 @@
 /*
-* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
-*/
+ * Copyright 2014-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
 
 package io.ktor.server.application
 
@@ -8,7 +8,6 @@ import io.ktor.server.routing.*
 import io.ktor.util.*
 import io.ktor.util.internal.*
 import io.ktor.util.pipeline.*
-import io.ktor.utils.io.core.*
 import kotlinx.coroutines.*
 
 /**
@@ -230,7 +229,7 @@ public fun <A : Pipeline<*, PipelineCall>, B : Any, F : Any> A.uninstall(
 public fun <A : Pipeline<*, PipelineCall>, F : Any> A.uninstallPlugin(key: AttributeKey<F>) {
     val registry = attributes.getOrNull(pluginRegistryKey) ?: return
     val instance = registry.getOrNull(key) ?: return
-    if (instance is Closeable) {
+    if (instance is AutoCloseable) {
         instance.close()
     }
     registry.remove(key)