diff --git a/lib/nghttp2_http.c b/lib/nghttp2_http.c
index e3259514..23db1cbc 100644
--- a/lib/nghttp2_http.c
+++ b/lib/nghttp2_http.c
@@ -250,6 +250,11 @@ static int http_response_on_header(nghttp2_stream *stream, nghttp2_hd_nv *nv,
     break;
   }
   case NGHTTP2_TOKEN_CONTENT_LENGTH: {
+    if (stream->status_code == 204 || stream->status_code / 100 == 1 ||
+        (stream->status_code == 200 &&
+         (stream->http_flags & NGHTTP2_HTTP_FLAG_METH_CONNECT))) {
+      return NGHTTP2_ERR_HTTP_HEADER;
+    }
     if (stream->content_length != -1) {
       return NGHTTP2_ERR_HTTP_HEADER;
     }
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index c11ff922..064adbf9 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -10200,6 +10200,10 @@ void test_nghttp2_http_mandatory_headers(void) {
                                     MAKE_NV("content-length", "0")};
   const nghttp2_nv badhd_resnv[] = {MAKE_NV(":status", "200"),
                                     MAKE_NV("connection", "close")};
+  const nghttp2_nv cl1xx_resnv[] = {MAKE_NV(":status", "100"),
+                                    MAKE_NV("content-length", "0")};
+  const nghttp2_nv cl204_resnv[] = {MAKE_NV(":status", "204"),
+                                    MAKE_NV("content-length", "0")};
 
   /* test case for request */
   const nghttp2_nv nopath_reqnv[] = {MAKE_NV(":scheme", "https"),
@@ -10298,6 +10302,16 @@ void test_nghttp2_http_mandatory_headers(void) {
                                        NGHTTP2_STREAM_OPENING, badhd_resnv,
                                        ARRLEN(badhd_resnv));
 
+  /* response header has content-length with 100 status code */
+  check_nghttp2_http_recv_headers_fail(session, &deflater, 17,
+                                       NGHTTP2_STREAM_OPENING, cl1xx_resnv,
+                                       ARRLEN(cl1xx_resnv));
+
+  /* response header has content-length with 204 status code */
+  check_nghttp2_http_recv_headers_fail(session, &deflater, 19,
+                                       NGHTTP2_STREAM_OPENING, cl204_resnv,
+                                       ARRLEN(cl204_resnv));
+
   nghttp2_hd_deflate_free(&deflater);
 
   nghttp2_session_del(session);
@@ -11001,6 +11015,7 @@ void test_nghttp2_http_record_request_method(void) {
   nghttp2_bufs bufs;
   nghttp2_hd_deflater deflater;
   nghttp2_mem *mem;
+  nghttp2_outbound_item *item;
 
   mem = nghttp2_mem_default();
   frame_pack_bufs_init(&bufs);
@@ -11033,6 +11048,14 @@ void test_nghttp2_http_record_request_method(void) {
   CU_ASSERT((NGHTTP2_HTTP_FLAG_METH_CONNECT & stream->http_flags) > 0);
   CU_ASSERT(-1 == stream->content_length);
 
+  /* content-length is now allowed in 200 response to a CONNECT
+     request */
+  item = nghttp2_session_get_next_ob_item(session);
+
+  CU_ASSERT(NULL != item);
+  CU_ASSERT(NGHTTP2_RST_STREAM == item->frame.hd.type);
+  CU_ASSERT(NGHTTP2_PROTOCOL_ERROR == item->frame.rst_stream.error_code);
+
   nghttp2_hd_deflate_free(&deflater);
   nghttp2_session_del(session);
   nghttp2_bufs_free(&bufs);