diff --git a/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2ServerDowngrader.java b/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2ServerDowngrader.java
index 2f0aecc3b8..affaeb1c0b 100644
--- a/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2ServerDowngrader.java
+++ b/codec-http2/src/main/java/io/netty/handler/codec/http2/Http2ServerDowngrader.java
@@ -24,8 +24,12 @@ import io.netty.handler.codec.http.DefaultLastHttpContent;
 import io.netty.handler.codec.http.FullHttpRequest;
 import io.netty.handler.codec.http.FullHttpResponse;
 import io.netty.handler.codec.http.HttpContent;
+import io.netty.handler.codec.http.HttpHeaderNames;
+import io.netty.handler.codec.http.HttpHeaderValues;
 import io.netty.handler.codec.http.HttpObject;
+import io.netty.handler.codec.http.HttpRequest;
 import io.netty.handler.codec.http.HttpResponse;
+import io.netty.handler.codec.http.HttpUtil;
 import io.netty.handler.codec.http.HttpVersion;
 import io.netty.handler.codec.http.LastHttpContent;
 import io.netty.util.ReferenceCountUtil;
@@ -78,9 +82,12 @@ public class Http2ServerDowngrader extends MessageToMessageCodec<Http2StreamFram
                     out.add(full);
                 }
             } else {
-                out.add(HttpConversionUtil.toHttpRequest(id, headersFrame.headers(), validateHeaders));
+                HttpRequest req = HttpConversionUtil.toHttpRequest(id, headersFrame.headers(), validateHeaders);
+                if (!HttpUtil.isContentLengthSet(req)) {
+                    req.headers().add(HttpHeaderNames.TRANSFER_ENCODING, HttpHeaderValues.CHUNKED);
+                }
+                out.add(req);
             }
-
         } else if (frame instanceof Http2DataFrame) {
             Http2DataFrame dataFrame = (Http2DataFrame) frame;
             if (dataFrame.isEndStream()) {
diff --git a/codec-http2/src/test/java/io/netty/handler/codec/http2/Http2ServerDowngraderTest.java b/codec-http2/src/test/java/io/netty/handler/codec/http2/Http2ServerDowngraderTest.java
index 3d3cf0127a..8aeeccf252 100644
--- a/codec-http2/src/test/java/io/netty/handler/codec/http2/Http2ServerDowngraderTest.java
+++ b/codec-http2/src/test/java/io/netty/handler/codec/http2/Http2ServerDowngraderTest.java
@@ -32,6 +32,7 @@ import io.netty.handler.codec.http.HttpRequest;
 import io.netty.handler.codec.http.HttpResponse;
 import io.netty.handler.codec.http.HttpResponseStatus;
 import io.netty.handler.codec.http.HttpVersion;
+import io.netty.handler.codec.http.HttpUtil;
 import io.netty.handler.codec.http.LastHttpContent;
 import io.netty.util.CharsetUtil;
 
@@ -255,6 +256,28 @@ public class Http2ServerDowngraderTest {
         assertThat(request.method(), is(HttpMethod.GET));
         assertThat(request.protocolVersion(), is(HttpVersion.HTTP_1_1));
         assertFalse(request instanceof FullHttpRequest);
+        assertTrue(HttpUtil.isTransferEncodingChunked(request));
+
+        assertThat(ch.readInbound(), is(nullValue()));
+        assertFalse(ch.finish());
+    }
+
+    @Test
+    public void testDowngradeHeadersWithContentLength() throws Exception {
+        EmbeddedChannel ch = new EmbeddedChannel(new Http2ServerDowngrader());
+        Http2Headers headers = new DefaultHttp2Headers();
+        headers.path("/");
+        headers.method("GET");
+        headers.setInt("content-length", 0);
+
+        assertTrue(ch.writeInbound(new DefaultHttp2HeadersFrame(headers)));
+
+        HttpRequest request = ch.readInbound();
+        assertThat(request.uri(), is("/"));
+        assertThat(request.method(), is(HttpMethod.GET));
+        assertThat(request.protocolVersion(), is(HttpVersion.HTTP_1_1));
+        assertFalse(request instanceof FullHttpRequest);
+        assertFalse(HttpUtil.isTransferEncodingChunked(request));
 
         assertThat(ch.readInbound(), is(nullValue()));
         assertFalse(ch.finish());
@@ -276,6 +299,7 @@ public class Http2ServerDowngraderTest {
             assertThat(request.protocolVersion(), is(HttpVersion.HTTP_1_1));
             assertThat(request.content().readableBytes(), is(0));
             assertTrue(request.trailingHeaders().isEmpty());
+            assertFalse(HttpUtil.isTransferEncodingChunked(request));
         } finally {
             request.release();
         }