diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/SystemDefaultDnsResolver.java b/httpclient5/src/main/java/org/apache/hc/client5/http/SystemDefaultDnsResolver.java
index 6a4d293573..7430c9bf7b 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/SystemDefaultDnsResolver.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/SystemDefaultDnsResolver.java
@@ -26,6 +26,7 @@
  */
 package org.apache.hc.client5.http;
 
+import java.net.IDN;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 
@@ -44,8 +45,9 @@ public class SystemDefaultDnsResolver implements DnsResolver {
     @Override
     public InetAddress[] resolve(final String host) throws UnknownHostException {
         try {
+            final String normalizedHost = IDN.toASCII(host);
             // Try resolving using the default resolver
-            return InetAddress.getAllByName(host);
+            return InetAddress.getAllByName(normalizedHost);
         } catch (final UnknownHostException e) {
             // If default resolver fails, try stripping the IPv6 zone ID and resolving again
             String strippedHost = null;
diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/io/DefaultHttpClientConnectionOperator.java b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/io/DefaultHttpClientConnectionOperator.java
index 1f20eccb6f..33a4cfcf82 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/io/DefaultHttpClientConnectionOperator.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/io/DefaultHttpClientConnectionOperator.java
@@ -27,12 +27,10 @@
 package org.apache.hc.client5.http.impl.io;
 
 import java.io.IOException;
-import java.net.IDN;
 import java.net.InetSocketAddress;
 import java.net.Proxy;
 import java.net.Socket;
 import java.net.SocketAddress;
-import java.net.UnknownHostException;
 import java.util.Collections;
 import java.util.List;
 
@@ -165,20 +163,13 @@ public void connect(
         final SocketAddress socksProxyAddress = socketConfig.getSocksProxyAddress();
         final Proxy socksProxy = socksProxyAddress != null ? new Proxy(Proxy.Type.SOCKS, socksProxyAddress) : null;
 
-        final String normalizedHost;
-        try {
-            normalizedHost = IDN.toASCII(endpointHost.getHostName());
-        } catch (final IllegalArgumentException e) {
-            throw new UnknownHostException("Invalid IDN hostname: " + endpointHost.getHostName());
-        }
-
         final List<InetSocketAddress> remoteAddresses;
         if (endpointHost.getAddress() != null) {
             remoteAddresses = Collections.singletonList(
                     new InetSocketAddress(endpointHost.getAddress(), this.schemePortResolver.resolve(endpointHost.getSchemeName(), endpointHost)));
         } else {
             final int port = this.schemePortResolver.resolve(endpointHost.getSchemeName(), endpointHost);
-            remoteAddresses = this.dnsResolver.resolve(normalizedHost, port);
+            remoteAddresses = this.dnsResolver.resolve(endpointHost.getHostName(), port);
         }
         for (int i = 0; i < remoteAddresses.size(); i++) {
             final InetSocketAddress remoteAddress = remoteAddresses.get(i);
diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/MultihomeIOSessionRequester.java b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/MultihomeIOSessionRequester.java
index fde1c699c8..4b8172c4ce 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/MultihomeIOSessionRequester.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/nio/MultihomeIOSessionRequester.java
@@ -28,7 +28,6 @@
 package org.apache.hc.client5.http.impl.nio;
 
 import java.io.IOException;
-import java.net.IDN;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
@@ -108,11 +107,10 @@ public void cancelled() {
         if (LOG.isDebugEnabled()) {
             LOG.debug("{} resolving remote address", remoteEndpoint.getHostName());
         }
-        final String normalizedHost;
+
         final List<InetSocketAddress> remoteAddresses;
         try {
-            normalizedHost = IDN.toASCII(remoteEndpoint.getHostName());
-            remoteAddresses = dnsResolver.resolve(normalizedHost, remoteEndpoint.getPort());
+            remoteAddresses = dnsResolver.resolve(remoteEndpoint.getHostName(), remoteEndpoint.getPort());
             if (remoteAddresses == null || remoteAddresses.isEmpty()) {
                 throw new UnknownHostException(remoteEndpoint.getHostName());
             }