diff --git a/codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectEncoder.java b/codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectEncoder.java
index 970db26f9e..98b6c9dafe 100644
--- a/codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectEncoder.java
+++ b/codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectEncoder.java
@@ -125,11 +125,17 @@ public abstract class HttpObjectEncoder<H extends HttpMessage> extends MessageTo
     }
 
     private static void encodeHeader(ByteBuf buf, String header, String value) {
-        buf.writeBytes(header.getBytes(CharsetUtil.US_ASCII));
+        encodeAscii(header, buf);
         buf.writeBytes(HEADER_SEPARATOR);
-        buf.writeBytes(value.getBytes(CharsetUtil.US_ASCII));
+        encodeAscii(value, buf);
         buf.writeBytes(CRLF);
     }
 
+    private static void encodeAscii(String s, ByteBuf buf) {
+        for (int i = 0; i < s.length(); i++) {
+            buf.writeByte(s.charAt(i));
+        }
+    }
+
     protected abstract void encodeInitialLine(ByteBuf buf, H message) throws Exception;
 }