diff --git a/include/haproxy/htx.h b/include/haproxy/htx.h
index 0fd1a1b97..339f0a559 100644
--- a/include/haproxy/htx.h
+++ b/include/haproxy/htx.h
@@ -30,6 +30,11 @@
 #include <haproxy/http-t.h>
 #include <haproxy/htx-t.h>
 
+/* ->extra field value when the payload lenght is unknown (non-chunked message
+ * with no "Content-length" header)
+ */
+#define HTX_UNKOWN_PAYLOAD_LENGTH ULLONG_MAX
+
 extern struct htx htx_empty;
 
 struct htx_blk *htx_defrag(struct htx *htx, struct htx_blk *blk, uint32_t info);
diff --git a/src/h1_htx.c b/src/h1_htx.c
index 1b79584a3..5e7f1ad5e 100644
--- a/src/h1_htx.c
+++ b/src/h1_htx.c
@@ -208,9 +208,9 @@ static int h1_postparse_req_hdrs(struct h1m *h1m, union h1_sl *h1sl, struct htx
 	}
 
 	/* If body length cannot be determined, set htx->extra to
-	 * ULLONG_MAX. This value is impossible in other cases.
+	 * HTX_UNKOWN_PAYLOAD_LENGTH. This value is impossible in other cases.
 	 */
-	htx->extra = ((h1m->flags & H1_MF_XFER_LEN) ? h1m->curr_len : ULLONG_MAX);
+	htx->extra = ((h1m->flags & H1_MF_XFER_LEN) ? h1m->curr_len : HTX_UNKOWN_PAYLOAD_LENGTH);
 
   end:
 	return 1;
@@ -306,9 +306,9 @@ static int h1_postparse_res_hdrs(struct h1m *h1m, union h1_sl *h1sl, struct htx
 	sl->info.res.status = code;
 
 	/* If body length cannot be determined, set htx->extra to
-	 * ULLONG_MAX. This value is impossible in other cases.
+	 * HTX_UNKOWN_PAYLOAD_LENGTH. This value is impossible in other cases.
 	 */
-	htx->extra = ((h1m->flags & H1_MF_XFER_LEN) ? h1m->curr_len : ULLONG_MAX);
+	htx->extra = ((h1m->flags & H1_MF_XFER_LEN) ? h1m->curr_len : HTX_UNKOWN_PAYLOAD_LENGTH);
 
   end:
 	return 1;
diff --git a/src/hlua.c b/src/hlua.c
index e5c6c93b6..346722675 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -4890,7 +4890,7 @@ static int hlua_applet_http_new(lua_State *L, struct appctx *ctx)
 		if (type == HTX_BLK_DATA)
 			len += htx_get_blksz(blk);
 	}
-	if (htx->extra != ULLONG_MAX)
+	if (htx->extra != HTX_UNKOWN_PAYLOAD_LENGTH)
 		len += htx->extra;
 
 	/* Stores the request path. */
diff --git a/src/http_fetch.c b/src/http_fetch.c
index 27cfe5473..8c01e0343 100644
--- a/src/http_fetch.c
+++ b/src/http_fetch.c
@@ -679,7 +679,7 @@ static int smp_fetch_body_size(const struct arg *args, struct sample *smp, const
 		if (type == HTX_BLK_DATA)
 			len += htx_get_blksz(blk);
 	}
-	if (htx->extra != ULLONG_MAX)
+	if (htx->extra != HTX_UNKOWN_PAYLOAD_LENGTH)
 		len += htx->extra;
 
 	smp->data.type = SMP_T_SINT;
diff --git a/src/mux_h2.c b/src/mux_h2.c
index 4c29a2815..ffbde4619 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -6356,7 +6356,7 @@ static size_t h2_snd_buf(struct stconn *sc, struct buffer *buf, size_t count, in
 	if (!(h2s->flags & H2_SF_OUTGOING_DATA) && count)
 		h2s->flags |= H2_SF_OUTGOING_DATA;
 
-	if (htx->extra && htx->extra != ULLONG_MAX)
+	if (htx->extra && htx->extra != HTX_UNKOWN_PAYLOAD_LENGTH)
 		h2s->flags |= H2_SF_MORE_HTX_DATA;
 	else
 		h2s->flags &= ~H2_SF_MORE_HTX_DATA;