diff --git a/include/haproxy/stconn.h b/include/haproxy/stconn.h
index 3b24b217e..4e8722e4a 100644
--- a/include/haproxy/stconn.h
+++ b/include/haproxy/stconn.h
@@ -457,13 +457,13 @@ static inline void sc_have_room(struct stconn *sc)
  * SE_FL_HAVE_NO_DATA to be called again as soon as SC_FL_NEED_ROOM is cleared.
  *
  * The caller is responsible to specified the amount of free space required to
- * progress. However, to be sure the SC can be unblocked a max value cannot be
- * eceeded : (BUFSIZE - RESERVE - HTX OVERHEAD)
+ * progress. It must take care to not exceed the buffer size.
  */
 static inline void sc_need_room(struct stconn *sc, ssize_t room_needed)
 {
 	sc->flags |= SC_FL_NEED_ROOM;
-	sc->room_needed = MIN((ssize_t)(global.tune.bufsize - global.tune.maxrewrite - sizeof(struct htx)), room_needed);
+	BUG_ON_HOT(room_needed > (ssize_t)global.tune.bufsize);
+	sc->room_needed = room_needed;
 }
 
 /* The stream endpoint indicates that it's ready to consume data from the