diff --git a/include/common/h2.h b/include/common/h2.h
index 1ef57b552..71be8ce78 100644
--- a/include/common/h2.h
+++ b/include/common/h2.h
@@ -181,11 +181,11 @@ enum h2_err {
 
 /* various protocol processing functions */
 
-int h2_make_h1_request(struct http_hdr *list, char *out, int osize, unsigned int *msgf);
+int h2_make_h1_request(struct http_hdr *list, char *out, int osize, unsigned int *msgf, unsigned long long *body_len);
 int h2_make_h1_trailers(struct http_hdr *list, char *out, int osize);
 int h2_parse_cont_len_header(unsigned int *msgf, struct ist *value, unsigned long long *body_len);
-int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *msgf);
-int h2_make_htx_response(struct http_hdr *list, struct htx *htx, unsigned int *msgf);
+int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *msgf, unsigned long long *body_len);
+int h2_make_htx_response(struct http_hdr *list, struct htx *htx, unsigned int *msgf, unsigned long long *body_len);
 int h2_make_htx_trailers(struct http_hdr *list, struct htx *htx);
 
 /*
diff --git a/src/h2.c b/src/h2.c
index 72b2dc613..1a103e49e 100644
--- a/src/h2.c
+++ b/src/h2.c
@@ -130,7 +130,7 @@ static int h2_prepare_h1_reqline(uint32_t fields, struct ist *phdr, char **ptr,
  * The Cookie header will be reassembled at the end, and for this, the <list>
  * will be used to create a linked list, so its contents may be destroyed.
  */
-int h2_make_h1_request(struct http_hdr *list, char *out, int osize, unsigned int *msgf)
+int h2_make_h1_request(struct http_hdr *list, char *out, int osize, unsigned int *msgf, unsigned long long *body_len)
 {
 	struct ist phdr_val[H2_PHDR_NUM_ENTRIES];
 	char *out_end = out + osize;
@@ -191,9 +191,14 @@ int h2_make_h1_request(struct http_hdr *list, char *out, int osize, unsigned int
 		if (isteq(list[idx].n, ist("host")))
 			fields |= H2_PHDR_FND_HOST;
 
-		if ((*msgf & (H2_MSGF_BODY|H2_MSGF_BODY_TUNNEL|H2_MSGF_BODY_CL)) == H2_MSGF_BODY &&
-		    isteq(list[idx].n, ist("content-length")))
-			*msgf |= H2_MSGF_BODY_CL;
+		if (isteq(list[idx].n, ist("content-length"))) {
+			ret = h2_parse_cont_len_header(msgf, &list[idx].v, body_len);
+			if (ret < 0)
+				goto fail;
+
+			if (ret == 0)
+				continue; // skip this duplicate
+		}
 
 		/* these ones are forbidden in requests (RFC7540#8.1.2.2) */
 		if (isteq(list[idx].n, ist("connection")) ||
@@ -556,7 +561,7 @@ static struct htx_sl *h2_prepare_htx_reqline(uint32_t fields, struct ist *phdr,
  * The Cookie header will be reassembled at the end, and for this, the <list>
  * will be used to create a linked list, so its contents may be destroyed.
  */
-int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *msgf)
+int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *msgf, unsigned long long *body_len)
 {
 	struct ist phdr_val[H2_PHDR_NUM_ENTRIES];
 	uint32_t fields; /* bit mask of H2_PHDR_FND_* */
@@ -567,7 +572,6 @@ int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *ms
 	int i;
 	struct htx_sl *sl = NULL;
 	unsigned int sl_flags = 0;
-	unsigned long long body_len;
 
 	lck = ck = -1; // no cookie for now
 	fields = 0;
@@ -620,7 +624,7 @@ int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *ms
 			fields |= H2_PHDR_FND_HOST;
 
 		if (isteq(list[idx].n, ist("content-length"))) {
-			ret = h2_parse_cont_len_header(msgf, &list[idx].v, &body_len);
+			ret = h2_parse_cont_len_header(msgf, &list[idx].v, body_len);
 			if (ret < 0)
 				goto fail;
 
@@ -784,7 +788,7 @@ static struct htx_sl *h2_prepare_htx_stsline(uint32_t fields, struct ist *phdr,
  *   - in all cases except the end of list, v.name and v.len must designate a
  *     valid value.
  */
-int h2_make_htx_response(struct http_hdr *list, struct htx *htx, unsigned int *msgf)
+int h2_make_htx_response(struct http_hdr *list, struct htx *htx, unsigned int *msgf, unsigned long long *body_len)
 {
 	struct ist phdr_val[H2_PHDR_NUM_ENTRIES];
 	uint32_t fields; /* bit mask of H2_PHDR_FND_* */
@@ -794,7 +798,6 @@ int h2_make_htx_response(struct http_hdr *list, struct htx *htx, unsigned int *m
 	int i;
 	struct htx_sl *sl = NULL;
 	unsigned int sl_flags = 0;
-	unsigned long long body_len;
 
 	fields = 0;
 	for (idx = 0; list[idx].n.len != 0; idx++) {
@@ -843,7 +846,7 @@ int h2_make_htx_response(struct http_hdr *list, struct htx *htx, unsigned int *m
 		}
 
 		if (isteq(list[idx].n, ist("content-length"))) {
-			ret = h2_parse_cont_len_header(msgf, &list[idx].v, &body_len);
+			ret = h2_parse_cont_len_header(msgf, &list[idx].v, body_len);
 			if (ret < 0)
 				goto fail;
 
diff --git a/src/mux_h2.c b/src/mux_h2.c
index 5754f79c2..c0b62303b 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -270,7 +270,7 @@ static int h2_recv(struct h2c *h2c);
 static int h2_process(struct h2c *h2c);
 static struct task *h2_io_cb(struct task *t, void *ctx, unsigned short state);
 static inline struct h2s *h2c_st_by_id(struct h2c *h2c, int id);
-static int h2c_decode_headers(struct h2c *h2c, struct buffer *rxbuf, uint32_t *flags);
+static int h2c_decode_headers(struct h2c *h2c, struct buffer *rxbuf, uint32_t *flags, unsigned long long *body_len);
 static int h2_frt_transfer_data(struct h2s *h2s);
 static struct task *h2_deferred_shut(struct task *t, void *ctx, unsigned short state);
 static struct h2s *h2c_bck_stream_new(struct h2c *h2c, struct conn_stream *cs, struct session *sess);
@@ -1893,6 +1893,7 @@ static int h2c_handle_rst_stream(struct h2c *h2c, struct h2s *h2s)
 static struct h2s *h2c_frt_handle_headers(struct h2c *h2c, struct h2s *h2s)
 {
 	struct buffer rxbuf = BUF_NULL;
+	unsigned long long body_len = 0;
 	uint32_t flags = 0;
 	int error;
 
@@ -1913,7 +1914,7 @@ static struct h2s *h2c_frt_handle_headers(struct h2c *h2c, struct h2s *h2s)
 	if (h2s->st != H2_SS_IDLE) {
 		/* The stream exists/existed, this must be a trailers frame */
 		if (h2s->st != H2_SS_CLOSED) {
-			if (h2c_decode_headers(h2c, &h2s->rxbuf, &h2s->flags) <= 0)
+			if (h2c_decode_headers(h2c, &h2s->rxbuf, &h2s->flags, &body_len) <= 0)
 				goto out;
 			goto done;
 		}
@@ -1930,7 +1931,7 @@ static struct h2s *h2c_frt_handle_headers(struct h2c *h2c, struct h2s *h2s)
 	else if (h2c->flags & H2_CF_DEM_TOOMANY)
 		goto out; // IDLE but too many cs still present
 
-	error = h2c_decode_headers(h2c, &rxbuf, &flags);
+	error = h2c_decode_headers(h2c, &rxbuf, &flags, &body_len);
 
 	/* unrecoverable error ? */
 	if (h2c->st0 >= H2_CS_ERROR)
@@ -2001,6 +2002,7 @@ static struct h2s *h2c_frt_handle_headers(struct h2c *h2c, struct h2s *h2s)
  */
 static struct h2s *h2c_bck_handle_headers(struct h2c *h2c, struct h2s *h2s)
 {
+	unsigned long long body_len = 0;
 	int error;
 
 	if (!h2c->dfl) {
@@ -2016,7 +2018,7 @@ static struct h2s *h2c_bck_handle_headers(struct h2c *h2c, struct h2s *h2s)
 	if (b_data(&h2c->dbuf) < h2c->dfl && !b_full(&h2c->dbuf))
 		return NULL; // incomplete frame
 
-	error = h2c_decode_headers(h2c, &h2s->rxbuf, &h2s->flags);
+	error = h2c_decode_headers(h2c, &h2s->rxbuf, &h2s->flags, &body_len);
 
 	/* unrecoverable error ? */
 	if (h2c->st0 >= H2_CS_ERROR)
@@ -3271,7 +3273,7 @@ static void h2_shutw(struct conn_stream *cs, enum cs_shw_mode mode)
  * decoding, in order to detect if we're dealing with a headers or a trailers
  * block (the trailers block appears after H2_SF_HEADERS_RCVD was seen).
  */
-static int h2c_decode_headers(struct h2c *h2c, struct buffer *rxbuf, uint32_t *flags)
+static int h2c_decode_headers(struct h2c *h2c, struct buffer *rxbuf, uint32_t *flags, unsigned long long *body_len)
 {
 	const uint8_t *hdrs = (uint8_t *)b_head(&h2c->dbuf);
 	struct buffer *tmp = get_trash_chunk();
@@ -3431,12 +3433,12 @@ next_frame:
 	if (htx) {
 		/* HTX mode */
 		if (h2c->flags & H2_CF_IS_BACK)
-			outlen = h2_make_htx_response(list, htx, &msgf);
+			outlen = h2_make_htx_response(list, htx, &msgf, body_len);
 		else
-			outlen = h2_make_htx_request(list, htx, &msgf);
+			outlen = h2_make_htx_request(list, htx, &msgf, body_len);
 	} else {
 		/* HTTP/1 mode */
-		outlen = h2_make_h1_request(list, b_tail(rxbuf), try, &msgf);
+		outlen = h2_make_h1_request(list, b_tail(rxbuf), try, &msgf, body_len);
 		if (outlen > 0)
 			b_add(rxbuf, outlen);
 	}