diff --git a/microbench/src/main/java/io/netty/handler/codec/http2/HpackDecoderBenchmark.java b/microbench/src/main/java/io/netty/handler/codec/http2/HpackDecoderBenchmark.java
index 7a94def517..8a8241413f 100644
--- a/microbench/src/main/java/io/netty/handler/codec/http2/HpackDecoderBenchmark.java
+++ b/microbench/src/main/java/io/netty/handler/codec/http2/HpackDecoderBenchmark.java
@@ -72,7 +72,7 @@ public class HpackDecoderBenchmark extends AbstractMicrobenchmark {
     @Benchmark
     @BenchmarkMode(Mode.Throughput)
     public void decode(final Blackhole bh) throws Http2Exception {
-        HpackDecoder hpackDecoder = new HpackDecoder(DEFAULT_HEADER_LIST_SIZE);
+        HpackDecoder hpackDecoder = new HpackDecoder(Integer.MAX_VALUE);
         @SuppressWarnings("unchecked")
         Http2Headers headers =
                 new DefaultHttp2Headers() {
diff --git a/microbench/src/main/java/io/netty/handler/codec/http2/HpackHeader.java b/microbench/src/main/java/io/netty/handler/codec/http2/HpackHeader.java
index c0b63590d4..482db41a59 100644
--- a/microbench/src/main/java/io/netty/handler/codec/http2/HpackHeader.java
+++ b/microbench/src/main/java/io/netty/handler/codec/http2/HpackHeader.java
@@ -40,14 +40,14 @@ import java.util.Random;
 /**
  * Helper class representing a single header entry. Used by the benchmarks.
  */
-class HpackHeader {
+final class HpackHeader {
     private static final String ALPHABET =
             "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_";
 
     final CharSequence name;
     final CharSequence value;
 
-    HpackHeader(byte[] name, byte[] value) {
+    private HpackHeader(byte[] name, byte[] value) {
         this.name = new AsciiString(name, false);
         this.value = new AsciiString(value, false);
     }
@@ -59,7 +59,8 @@ class HpackHeader {
                                            boolean limitToAscii) {
         List<HpackHeader> hpackHeaders = new ArrayList<HpackHeader>(numHeaders);
         for (int i = 0; i < numHeaders; ++i) {
-            byte[] name = randomBytes(new byte[nameLength], limitToAscii);
+            // Force always ascii for header names
+            byte[] name = randomBytes(new byte[nameLength], true);
             byte[] value = randomBytes(new byte[valueLength], limitToAscii);
             hpackHeaders.add(new HpackHeader(name, value));
         }